iTube is the latest addition to iFi Audio ‘Micro’ line of audio gears. On one hand, it inhere the same minimalistic concept as the other Micro gears; on the other hand, it is a departure from the previous all-solid-state design. If anything, it is the first in Micro gears that will appeal more toward speaker user rather than headphone user. So what exactly does an iTube do? In essence, it is a tube buffer / pre-amp, with some extra features threw in.



Spec
Input voltage: AC 100-240v, 50/60Hz
Power consumption: under 4W Idle, 10W max
Input impedance: 1M ohm Direct Tube Buffer / 100k ohm Pre Amplifier with Volume Control
Output stage output impedance: less than 1 ohm
Corrected output impedance: Less than 200 ohm
Dimensions: 175(l) x 67 (w) x 28 (h) mm
Weight: 278g (0.61lbs)
MSRP: US$299





Gain - Buffer or Pre-amp
Like the newer iCAN, there is a user selectable gain switch on the belly of the housing. However, the switch also enable / disable the volume pot on the iTube, allowing it to run either as a Class A tube buffer or a pre-amp. In both modes, you can also choose either zero or +6dB gain, depends on how strong your source’s signal is. Of course, you will have to take into account whether the output will clip the input of the next device (which will be an amp or an amp section on an active speaker). My suggestion is, if your source has a 2V line level signal or something near it, keeps it at zero gain. If your source has a weak signal (i.e. older iPods only have only a 0.55V line-out), gives it the +6dB gain.

As for whether to use it as a pure buffer or pre-amp will depend on the gears you are connecting the iTube to. If it is feeding to a power amp that has no volume control of its own, then obviously you should use iTube in pre-amp mode to control the volume. If however the iTube is feeding into an active speaker that has its own volume control, then iTube should be configured as buffer. Note that the volume pot also doubles as the on/off switch, so you still need to turn it on even in the buffer mode, though volume will not be changed at all. As with all tube gears however, you should try to avoid rapid or frequent on/off action as much as possible in order to prolong the tube operational lifespan. If you are only going away for a short while, instead of turning it off, it might be better just to leave it on.



Sound Quality
Tube is always associated with noise and harmonic – in a way iTube is about those as well, but more on the harmonic and less on the noise. For measurement, I set the iTube up in a full iFi chain – staring with iUSB Power, which connected to the iDAC via the Gemini dual head USB cable. The line-out of the iDAC is fed into the iTube as a buffer, then to the iCAN with a 23.5 ohm dummy load. RMAA measurement is done with both the iTube in chain and without it for the comparison. Surprisingly, the impact of iTube, at least on graph, seems to be fairly minimum. Yes, it is noisier with the iTube, but we are talking about 0.001% of difference in THD and 0.004% in IMD+Noise, plus less than 2dBA in overall noise level. The numbers are small enough that I have to wonder how valid they will be in actual listening. As far as the frequency response goes, iTube is as flat as it can be, at least when the Digital Antidote Plus is not engaged (*but we will leave that discussion to the next section).

The actually listening experience with iTube however is a much less subtle business. Beside the setup mentioned above (plus a pair of Sony MDR-1R and a few IEM), most of my audition of the iTube is done in buffer mode with a pair of Creative GigaWorks T40 Series II 2.0 desktop speaker with an additional Creative sub-woofer. The first thing to pick up with the iTube, and particularly noticeable with headphones, is the distinctive ‘tube’ sound. So what is this tube sound? Well, it is a general richness that isn’t there before, like switching from a standard definition to a high definition signal on TV. It is the same image, but there is more information that fills up the space. At first, the effect is not that apparent. But once I switched back from iTube+iCAN to iCAN only, and just like going from HD to SD signal, everything sounds duller and harsher, even though I have been enjoying iCAN by itself for months now. I guess this is what iFi has referred as the ‘voodoo’ of the tube sound - the kind of euphonism that is just hard to get rid of once you are hooked. This is probably what makes tube gear user return to tube time and time again.



EQ
There are two additional features that are packed into the iTube – the 3D HolographicSound (3DHS) System and Digital Antidote Plus – well, calling the Digital Antidote Plus an EQ might not be the most accurate, but just bear with me here.

Don’t confuse the 3DHS on the iCAN to iTube. Yes, both have the same name and supposed to enhance soundstage, but that’s just about where the similarities end. The 3DHS on the iCAN is tuned with headphone in mind, but the one on iTube is all about speaker. The ‘small’ setting is meant for floor speakers or monitors that are already placed far apart and the goal is to put out a better perceived separation on the lower frequency region. The ‘wide’ setting however is meant for desktop monitor (such as PC speaker) and is aimed to project a bigger overall image than the speaker usually can. You can of course choose whichever setting that fits your own speaker configuration and taste, but I do find the wide setting does show significant improvement over my T40 S-II (which is a desktop speaker). In a way it does a similar function as the software based virtual surround sound effect built into the Windows OS, but much better in result. While Windows (and a good number of software movie players) tends to try to create a more hollowed out image between the left and right speakers to create the illusion of space, the 3DHS ‘Wide’ on iTube is more about pushing out an image larger than the speaker’s physical placement, as if they are actually further apart. This works out better for music listening as the mid-range still retains its texture and intensity as opposite to a hollowed out sound. As with the 3DHS on iCAN, I am quite amazed by iFi ability to fine tune the analog circuit and be better than software solution. But the one thing to note is that this 3DHS is for speaker only. Trying to use it with headphone will mostly mess up the image instead of improving it (same can probably be said on iCAN’s 3DHS negative effect on speaker).



Digital Antidote Plus on the other hand is lesser of an EQ and more of a phase correction technique for digital source. The original idea of a ‘digital antidote’ comes from and patented by Anthony Taddeo of Taddeo Speakers in the early 90s to address the digititis of then popularized CD system. In simple terms, it involves splitting the analog signal from a digital source into two, delays one of them with a few milliseconds then recombines it back to the original signal in order to correct whatever phase error introduced in the digital stage and to recreate a ‘more analog like’ music reproduction. It had caused quite a stir in the audiophile’s community when it was first introduced, both positively and negatively, where some swear by it while other found the effect to be subtle at best. With the passing of Mr. Taddeo about 10 years ago and his company dissolved subsequently, the original Digital Antidote and the V2 hardware are no longer available. The Digital Antidote Plus (DAP) in the iTube is however a new take on the original concept and according to iFi, updated to be compatible to the latest and upcoming HD format of music.

So history asides, does the DAP work as advertised? Well, the first thing I did is to get some measurement off. RMAA is really not great on measuring beyond the basic stuff and certain not for phase - but one thing to look for is the treble roll-off that inheres from the original Digital Antidote circuit. As you can see from the graph, the area around 8kHz is actually bumped up by 0.4dB, then it drops off to -1dB around 15kHz before ending up at -2.5dB @ 20kHz. Given human is only sensitive to about 1dB of SPL change, the actual effect will be more noticeable above 15kHz. But since most human, especially adult, have likely lost a significant amount of hearing on the high treble region, the actual impact on listening should be relatively small. In real listening, my 30+ years-old ears really didn’t detect any major loss of treble from album to album. One thing I do pick up, and in a very obvious fashion, is the increase of texture and detail in the mid to bass range. This is most noticeable when I was listening to Piano Guys’ first and second album, where the decay and body of the piano and cello becoming unusually clear and their timbre becoming almost too good. To use the TV analogy again, it will be the equivalent of switching from HD to a 4K signal - Okay, perhaps this all seems to be too much of a hype. But it really isn’t about how SD to HD, or how HD to 4K that matters. It is about the increase of overall information from one to the other. With the iTube alone, it is like filling the background with all the missing notes. With the DAP engaged, it is like those notes are brought to the foreground. Is that how ‘analog sound’ should be, or is it a better approximation of live music that is somehow lost in the recording process in the digital era? I truly have no answer. But I can say I don’t dislike it. It is something that I can leave it on all the time and don’t feel like it has degraded the sound in any way. In fact, I think the result is really a plus to the overall music listening experience – regardless of whether it is an EQ, a phase correction or just another technological voodoo.

One last thing to note is that I can pick up the difference on DAP easier on the headphones than on the speaker. Then again, my headphones are generally better sounding and more revealing than my speaker. Your mileage however might differ.



…in Conclusion
I have a very small computer desk that also doubles as my working and listening area, and it is constantly full of all kind of gears and never enough in space. Early last week after receiving the iTube, I had the whole iFi chain setup on the desk for the iTube review and thought that I would have to disassemble them quickly in the next few days in order to reclaim the space back. The whole setup, as I am about to finish writing this review, is still sitting on the desk after almost 2 weeks. It could very well be staying there for a while longer, given how much music I have been enjoying recently over my Creative speaker - and to think that I am predominately an on-the-go IEM user. I guess this really sum up the iTube magic thingy. Sometime it is the seamlessly little stuffs that add up to make the whole experience worthwhile.

A thank to iFi Audio for the review sample

First, I want to thank Phiaton for the review sample.
 
As a headphone brand, Phiaton is relatively new to the scene. But as a company, it has a rather long history. Phiaton was setup by Cresyn Korea in 2008 as an initiative to launch its own high end headphone line. Up to that point, Cresyn has been very successful in the headphone OEM/ODM business all over the world, yet not quite known for their own brand of headphone. For a company that has been in the business for over 50 years and currently owns 5 manufacturing plants with 15 thousands employee, one can imagine Cresyn doesn't see Phiaton as a summer project, but rather want it to be a force to reckon with in the headphone business. It is their chance to showoff the company's audio and technological excellency.



[size=x-large]Spec[/size]
Driver: Single dynamic transducer
Frequency range: 10 Hz ~ 27,000 Hz
Impedance: 32 Ohm
THD: < 1% @ 1 kHz
Sensitivity: 98dB @ 1 kHz
Maximum input power: 30 mW
Weight: 0.29 oz / 8.2 g without cord
Connector: 3.5mm gold-plated mini jack.
Cable length: 115cm




[size=x-large]Packaging, Build Quality and Accessories[/size]
PS210 comes in a transparent plastic box with quite a small footprint. The earpieces are however, hold inside an inner paper box and showcased in their full glory. Not only the inner paper box is hold firmly by some smart design on the outer plastic box, the whole package also feels like an elaborate origami puzzle with only one place glued while the rest just folded into their own places. It just looks classier than simply blister packed and sealed the whole thing.



If you read my previous review on several Cresyn IEM models, you will know that there is really nothing to concern about when it comes to the much higher class PS210. The earpeice itself is half aluminum (where the turbine like design is) and half plastic (where the transducer is housed). The strain relief on the earpeice is a little hard but still adequate. The cable is quite tangle- and memory-free while not appears to be too springy or too soft. The Y-splitter is on the small side but the added aluminum cylinder gives it more 'substance'. If there is one place I would = like to see improvement, it will be the mini plug. The strain relief and overall build is decent but it is a little too small to handle regularly. I would prefer a longer plastic handle or a L-shaped plug as it will be easier for insertion and removal, not to mention the added durability.




Accessories are average in quantity. There is just 4 pair of different sized single flange eartips (XS, S, M, L) and a carrying case. The eartips are pretty decent, but I do prefer Sony Hybrid (or good quality clone in this case) for better seal and added warm to the sound - and for extra special, I find out that Comply T400 works wonder with both the fit and the sound, but let's keep this discussion to the next section. While the eartips might not be the best there are, the case is however a gorgeous looking leather pouch in cylinder shape. It is great to the touch and houses the IEM perfectly fine. The leather case itself really adds some class to the whole package.




Last but not least - Phiaton calls the PS210 earpieces' design "half in-ear", which is true in both design and actual audio performance sense. Similar design for dynamic transducer based IEM is not uncommon. From the more distanced Sony MDR-EX85 / EX90 to the closer looking Audio-Technica ATH-CKS70, the idea of this design arises from the need to place a relatively large dynamic transducer closer to the ear without actually jamming it in (nor the associated pain of course). The benefit of having a larger transducer is of course based on the simple concept that the extra room provides space for tuning and performance. What unique to PS210 is the openness of the design. As you can see in the picture, there are three small vents near the base of the nozzle (with grill underneath, I might add) - no doubt for sound tuning which we will also discuss in detail on the sound quality section. This feature truly makes the PS210 a "half in-ear" - you get the nozzle of a typical IEM which directs the sound into the ear canal, yet the vents make it performs a lot more like an earbuds. Needless to say, isolation is pretty weak on the PS210. The incomplete seal does make microphonics quite low.

Overall I am quite happy with PS210. Isolation is pretty disappointing but it is a trade off for PS210 unique sound quality. While an improved mini plug won't hurt, I think what I really want to see in the PS210 package is some Comply T400.



On a side note, PS210 is the winner of this year Red Dot Award. Interestingly enough, CKS70 won it last year. It would have been quite a showdown if Phiaton was able to submit the design last year when PS210 was already out.

[size=x-large]Sound Quality[/size]
As always, a 50 hours minimum burn-in session on the IEM before review and nothing major was detected. Let's begin with eartips selection - getting the good seal is often half way of getting a good sound. In this case, it is not quite about a good seal. The stock eartips are fine in my opinion, but a little 'lack of substance' as they don't give the kind of sound I like. For those who have listened to a pair of top-end Audio Technica (CM7, CM700) or Bang & Olufsen A8 earbuds before, PS210 will not sound unfamiliar. It is a kind of clean, extremely airy and specious sound with a very crisp treble and relatively lean by most of today standard, a kind of sound signature that has been extremely popular in East Asia and actually been highly thought of over more than a decade in the region. I am not sure whether it is Phiaton's deep Asian root or simply a coincidence, but I must say I am quite pleasantly surprised at the first listen to find that kind of sound signature in an IEM.

Through I have a fair share of love for A8 as an earbuds, I do however like a more balanced sound in my IEM, at least more balanced than the stock eartips can provide. A simple quick fix is the Sony Hybrid eartips (or similar good quality clone), which add more warmth and forwardness to the mid (with a little leftover for the bass) and smooth out some of the graininess on the top end. For a totally relaxing sound however, I prefer the T400. I am not a big Comply user myself (mainly because of the cost), but this really works very well with PS210. It pretty much smooth out all the graininess and mellow out the sound just enough for it to 'disappear in the ear' - which is always a great aspect for any IEM in my opinion. This combination is especially well for classical or instrumental music.

For those who prefer a fuller body mid and bass (i.e. vocal lover), there is a simple mod that can be very effective. Just cut a tiny piece of transparent tape and seal off one of the vents on the base of the nozzle (the first one closest to the nozzle is generally the easiest). I can assure you this will give a rather magical mid and well bodied bass that makes any Jazz singing comes alive. A little Blu-tack will actually give you the same effect, but I rather not recommend it in the long run.

The overall sound signature is analytical, clean, very airy and specious with crisp treble while relatively lean in the mid and bass departments. Treble is well extended and very crisp with slightly graininess on the top yet full of detail. Mid is slightly recessed, but not by much. Bass extends decently low with good speed, but doesn't quite have the impact, body or depth. Soundstage is very wide. To smooth down the graininess and add warmth and forwardness to the mid and bass, Sony Hybrid eartips is recommended. For a relaxing sound, Comply T400 is a good choice. Also, sealing one of the small vents adds the much needed body, depth and texture to the mid and bass.



[size=x-large]Verdict[/size]
There are so many simple ways that PS210 can be tuned to one's liking makes it a rather playful and enjoyable experience for me as both as listener and reviewer. Despite the fact that it doesn't have near enough isolation to actually be used in anywhere noisy, the "half in-ear" half earbuds-like quality of PS210 is what I consider a trade-off, not a total disadvantage from a sound quality point of view. PS210 will be a great choice for analytical listeners that are looking for openness that is not typically found in IEM and do not demand isolation, more so if you are willing to play around a bit. MSRP is $119 but street price can be as low as $95 - it is a no brainer for me.
 
A quick sum-up can be found here.

Before the review, I'll like to thank Phiaton for the loaner unit of PS320.
 
Prelude
I kind of think I have moved from chasing the next best thing to simply trying to get more enjoyment from what I have, but once in a while I get the chance to listen to something I feel really special. It doesn’t have to be particular high-end or expensive, just a sound that fulfill a person’s inner craving. Now I must first admit I am a fairly analytical listener. Not that I don’t enjoy a balanced or warm sound from time to time, I just find myself being drew back to micro detail and neutral presentation all too often.  Being a self-proclaimed audiophile for a while also let me to reach some conclusion of my own. One of such conclusion is: there is no such thing as an absolute ‘correct’ sound. If all of the best gears around can reproduce sound as truthfully to the original recording as possible, then the only logical conclusion will be - they should all sound the same. Yet it is never the case no matter how costly or exotic the gears are. If such ‘correct’ sound does exists for a person, it will likely to be a blend of the listener’s taste, synergy of gears, and the interpretation of faithfulness to the original recording. That being said, it is my belief that the right sound is the better sound, but the reverse might not be always true - especially for those who could only rely on another’s impression or review. Hopefully you will find this review useful because you understand a little more about me as a reviewer.
 
 

 

 
 
Spec
Frequency Response: 11Hz – 23Hz
Design: Closed
Driver: 13mm and 40mm Dual Dynamic with Passive Crossover
Max input power: 500 mW
Sensitivity: 102dB
Impedance:  32ohm
Isolation: -10dB ~ -12dB
Weight: 122 grams w/o cord
Connector: 3.5mm Gold Plated
Cable: Y-cord, 1.25m
 
 

 
 
Packaging, Accessories and Build Quality
Most likely because of the limited quantity of loaner unit, I actually received one without the outer packaging. While it really isn’t much I can say about something I never handle in person, I was fortune enough to see the actual package of PS320 (and a few of the Phiaton MS series as well, which by the way are some serious eyes candy) in a dealership before, not to mention I have reviewed one of the in-ear models from the same series before. I think I will still describe it the same way I did on my last Phiaton review - simple yet classy. It seems to be a theme Phiaton has on most, if not all of their products.
 
Accessories wise, PS320 comes up a little thin with only a leather soft pouch, though the pouch itself is a real beauty. I would really like to see Phiaton improves on the accessories department. As the brand itself is building toward a higher class of music listener, I think most buyer will want to see more than just the pouch. A 6.3mm and/or an airline adapter will be nice. It will be even better if replacement leather earpads are included as well. Some time little thing goes a long way.
 
Build quality is overall good on PS320. The leather pads on each side of the earcups are very nice touch. The hard plastic headband has metal pieces to support the structure. The joins are all well designed and don’t seem to have any particular weak spot. Both earpads and the cushion on top of the headband are extremely soft and comfortable. It is most definitely not a dead clamp on the head. It is pretty secure when walking around but I won’t take it for a run. The only downside is perhaps the single side cable. Though the original cable is fine to use, a more robust cable would have added a lot more point to the overall build.  Removable cable would also be a great idea.
 
Though fully closed, PS320’s isolation is right about average, so don’t expect IEM-like isolation. On average it is better than opened on-the-ear headphone, but it isn’t enough to give you a clean sound in subway or plane ride. It is however good enough for quiet home / office use or street with light traffic.
 
 

 

 
 
Sound Quality
Let be honest first, PS320 sound signature probably is not for everyone.  It is what I will describe as the on-ear equivalent of Etymotic. For those who are not familiar with the Etymotic sound, it is generally considered to be lean on the bottom while analytical on the top. While PS320 do not share a carbon copy of frequency response (FR) with any Etymotic, they do have some common characteristics, such as a quantitatively small yet very tight and accurate bass hit and an aggressive treble. The one thing, perhaps the one real sonic weakness on PS320 is the lack of any sense of warm or fullness. It is evidently bone dry. In fact, the dryness couples with the aggressiveness might make PS320 sounds just a little too ‘busy’ to some. That is, it lacks some fine resolution between notes. To me, it is not really an issue of resolution. The problem lies in the lack of good texture, thus the listener couldn’t properly hear each note. One of a quick fix is to give PS320 a little mid-bass bump. It doesn’t take much either, just EQ +2~3dB in the 250Hz region and we are cooking! While 2 or 3dB might not seem like much, the idea is to improves it just enough so the overall sound signature can remain as intact as possible. Just as a side note, PS320 does response to EQ very well. For people who don’t / can’t EQ, I have another trick for you on the next section when we discuss mod’ing.
 
One of the strong points of PS320 is the relatively neutral FR that extends very far to both ends, no doubt the benefit of having two drivers instead of one. Bass, though is not in abundance, is very precise and well extends to almost 20Hz. It is what I’ll like to describe as ‘quality bass’. Mid, as I have mentioned, can be just a tad too dry without EQ. While it is comparatively a weak spot in the whole sound signature, it is not really a turn down by any means. Treble pretty much goes as far as my hearing limitation at around 17.5Hz (till I can’t tell whether it is still going up or not).  It is very clean and sparkly, quite forward, bright and full of micro detail. This is by far the most linear of any headphone I have ever heard. Soundstage is decent, though nothing spectacular.
 
I find PS320 to be fine with most music genre that doesn’t require a good vocal and a heavy bass. Classical and instrumental music seems especially well because of how reveal PS320 is. With a little EQ however, even vocal and smooth jazz can be pretty good as well. Diana Krull and Sade actually both sound mighty fine in my ears. I didn’t find PS320 to be particularly hard to drive, so amping is not a necessity. Amped or not, I can’t say I find any weird sound frequency from the passive crossover. I probably won’t even notice there are two drivers simply by listening. Do note that you will be well to keep PS320 away from bad source and low bitrate. In my opinion a slightly warm source will probably have the best synergy.
 
 

Under the earpads: the coaxial 13mm treble unit on the front and 40mm bass unit visible in the vents
 

PS320 next to another dual driver, my mod'ed Panasonic VMSS headphone, which really isn't a match in SQ compared to the Phiaton.
 
The Mod
Here is a quick and pain-free mod for PS320 to add some warm to the sound. If you take a look at the picture where the earpad has been removed (by slowly prying them on one side, as they are just clipped onto the earcups), you can see 8 vents surrounding the treble driver. All you need is to cut some tissue up and cover 4 of those vents. My choice is the top and bottom’s two (in pair). No glue is needed; just clip the earpad back and the paper will be held in place. You can also vary the number of vents or the material you want to cover to achieve a sound you wanted.
 
Verdict
I am a fairly dedicated IEM user, have a few decent cans but never could really see myself converted to the other sides. However, there is something about PS320 that I do consider to be just right for me: It is portable, very comfortable and has a clean, neutral and highly detailed sound. More importantly, this is going for only $150 on the street now (MSRP is around $200). I don’t know how PS320 will fit your taste, but it is getting a thumb up from me. If you are an analytical listener like me, this will be a portable headphone I can truly recommend by heart. In fact, I am already setting my sight of picking one up in the future after the loaner unit goes back to Phiaton. Dual drivers or not, PS320 has turned out to be a great listening experience for me.

[Impression] miniwatt n4
The Hong Kong based company miniwatt has quite an interesting history as they have the tendency to focus on one product at a time. I actually won their first product a few years ago in a contest, and it was the tiny tube based speaker amp called S1. The n4 under review here however has nothing to do with tube anymore, but a DAC + headphone-amp aiming toward the PC audiophiles.
 

 
Spec
USB 2.0 Async Mode (driver required) supports up to 32bits/192k (upsampling)
DAC: PCM1795
DAC Filter and Headphone Driver: LM4562 with independent L and R channel circuit at output stage
Headphone Output: 100mW at 32Ohm
Line Output: 1.8V rms (auto mute when using headphone out)
USB 2.0 audio to S/PDIF converter, 32/192k SPDIF output
Digital Attenuation: 0 dB to –120 dB, 0.5db/Step
USB-powered, no external power supply required
Dimensions: 115mm (L) x 74mm (W) x 20mm (H)
Finish: CNC Silver Powder Coated Aluminium Panel with Laser Etching + Stitched Leather Extrusion
 

 
Packaging, Accessories and Build Quality
N4 comes with pretty much minimum packaging. As far as accessories goes, only a USB cable – which is fine for what it is. However, I wish miniwatt has included some kind of a quick start guide inside, or at least a piece of paper pointing to their website. While the n4 is pretty easy to setup, it does require a driver to run in Windows, and you can only get it from miniwatt’s website (which isn’t the easiest the find: miniwatt.com.hk)
 
The build quality is pretty good and rather unique in design. You have the 3.5mm headphone-out and volume control on the front; the USB input, RCA line-out and coax digital out on the back. The housing is aluminium but wrapped in PU leather, offering a nice exterior finishing.
 

You can see the stitches on the side.
 
SQ
Let’s talk about the hardware first. On paper, the n4 pretty much has all the goody you will want from a USB DAC of its price bucket – asynchronous USB mode, top-end TI’s DAC chip that will upsample everything to 32/192, a fairly powerful headphone driver based on the well regarded LM4562, pretty high line output, digital-out as well as digital volume control. So do these translate to actual performance? RMAA measurement on the headphone-out shows flat 20Hz to 20kHz frequency response, slightly higher Intermodulation distortion but nothing alerting, and otherwise very clean output. Max headphone-out is the same as line-out, at around 1.7Vrms. Output impedance is calculated to be well under 1 ohm. Output current is decent as well, not particularly high but should be quite enough even for low impedance IEM. Overall, everything seems to stand up to my basic measurement. But the one thing I do want to complain about is the digital volume control mechanism – on Windows 8.1 where you have 0 (mute) to 100 (max), the first few steps on the volume control simply are too loud. RE0, for an example, can only be listened at around volume 6~8, and it is worst for more sensitive IEM. Some of my IEM can’t even be listened at volume 1. I have to lower both the volume on the playback software as well as the Windows master volume control so I can have some finer control over the range. This is kind of far from the “0 dB to –120 dB, 0.5db/Step” quoted in the spec. The good news is that hiss is actually quite low even with sensitive IEM, but you probably won’t use such sensitive an IEM given the volume issue and therefore it is unlikely you are going to enjoy the benefit of the low hiss. Given the volume is fully digital, the line-out is also affected. To get the best out of it, you will want to max it out on the Windows setting when you are using n4 as a source to feed an amp.
 

 

 
So how does the n4 sound subjectively? On the line-out alone, it is pretty much what you can expect from what I’ll consider fairly classic TI’s top DAC will sound like – overall neutral with a sense of warmth and organic. Compared to the crisp and clean sounding ES9023 in the iFi Audio’s iDAC, the PCM1795 in n4 is smoother and not as revealing on the top, but carries a little bit more texture on the bass and mid. It might seems like a lot of difference on how I described them, but the truth is the difference between them is fairly subtle. You might not notice much if you don’t have some very revealing headphone in the first place. Simply put, iDAC would have more of a wow factor in first listening while n4 is more musical in the long run. Both are quite excellent on their own right.
 
So how is the headphone-out then? Well, it is definitely not quite as good as a standalone JDS labs O2, but still edges out just a bit over the headphone-out of iDAC. Compared to iDAC, n4’s headphone’s presentation is similar but grander - with wider soundstage and deeper reach into the bass region. It is fairly clean and neutral, if not just a little on the leaner side of things and kind of compensating the slight warmth from the DAC section. As mentioned before, my only complaint is the volume simply being too loud for sensitive headphone and IEM in my Windows 8.1 machine. I am not sure if it is the same for other Windows PC, but it is something miniwatt needs to look into.
 

Size comparison (from left): Leckerton Audio UHA-4, n4, FiiO E18.
 
Sum up
Despite the volume control issue, the n4 is a fairly well rounded bit of kit – it is well made, decent in design, and good in performance. The original price of almost $350 is however on the high side, consider you can get an O2+ODAC or iFi Audio iDAC for under $300 and both offer compatible performance. But the price has been lowered since early 2014 to $199 (directly from miniwatt's webstore), making the n4 much more attractive and easier to recommend. If miniwatt can take care of the volume issue, n4 will have no problem being one of the front runner of its class.
 
A thanks to miniwatt for the sample.

Some might not know this, but JAYS of Sweden is actually one of the earliest audiophile IEM manufacturer around, joining the game well before the whole IEM bloom of recent years. Though their first model was released in 2006, it was really the original q-JAYS in 2007 that put them on the map, right alongside big names like Ultimate Ears (with Jerry Harvey still at the helm and Triple.Fi 10 Pro being their cream of the crop), Westone (with their best offering, the UM2) and Etymotic (always the ER4 of course). But with the 2009 financial crisis and recession hitting Europe hard, JAYS switched gear and focused their attention to mid and lower-end offering while the q-JAYS was ultimately discontinued. It was not until early 2015 that the second generation of q-JAYS was finally announced and JAYS, as it seems, is finally ready to come back to the higher end market.
 

 
Spec
Driver: Custom Dual Balanced Armature
Sensitivity: 103dB @ 1kHz
Frequency Response: 5~20000Hz (Full Range) / 8~16000Hz (+/-5dB)
Impedance: 50 ohm @ 1kHz
Isolation: -40dB @ 2kHz
Housing: Stainless Steel with PVD Matte Finishing
Cable: 120cm User Replaceable Kevlar Cable with SSMCX Connector and Gold Plated 3.5mm Plug.
 

 
Packaging, Accessories and Build Quality
As always, being simple yet elegant is how JAYS like to present their products – no difference with the new q-JAYS on this aspect as well. I guess this is what the Nordic’s charm is all about – treating simplicity as a beauty of its own while doesn’t compromise in styling or functionality. Now that’s class.
 
Accessories wise, you’ll get all that are needed – a round hard case that holds the earpieces can also be used for storage once the inner foam is taken out. 5 pairs of silicone single flange eartips of various size and a pair of Comply foam tip. Last but not least - the removable cable. A few things to note: first, the marking of left and right channel on the cable isn’t easy to spot, so don’t put them in the wrong order. The earpiece itself doesn’t have any marking on them, but the curvy shape itself serves as an indicator on which is which. Of course, you can put them on the wrong orientation if you like it that way. It is up to you. Secondly, there are tiny o-ring on both the cable connector and the removable filter – you don’t want to lose those when replacing the cable or cleaning up the filter as they will not be easy to find (well, technically not hard to find either, but you’ll need to order a few hundreds of them at a time from some Chinese suppler specialize in o-ring even if they are dirt cheap).
 

 

 
Build quality is excellent, perhaps in many ways some of the best I have seen. On the old q-JAYS, there are a couple of known problems, namely (1) the cable harden over time and eventually will develop a fault right where it goes into the earpiece and (2) earwax clogging the replaceable stick-on fabric filter, which you will need to replace once in a while. The new q-JAYS seems to tackle these problem heads on with the new replaceable cable and removable (*plus clean- and reusable) laser cut metal filter. I am particularly glad to see JAYS didn’t cut corner on just using a (usually dreadful and often fragile) MMCX connector, but instead adapted and reengineered the SSMCX connector with a thread and screw mechanism. That gives the connector the mechanical strength it needs for use as a headphone cable and won’t likely to suffer the same kind of disconnecting / pin misalignment issue that plagues all MMCX connector. The metal filter is also excellent example of JAYS engineering capability where they choose to CNC and laser cut it out instead of going with the more conventional manufacturing process. Last but not least is the rather unassuming housing that is formed by stainless steel injection molding and followed by a matte finish using a special metal vapor deposit process. All and all, the attention to detail is unparalleled to all other IEM I have seen.
 

 

The removable laser cut filter and the internal acoustic filter.
 

 
Sound Quality
Sound signature wise, the new q-JAYS is somewhere between a neutral and a warm+sweet sound, with a slightly rich tone. Bass has good quality and reaches down deep to the 20Hz, but it is qualitatively just a bit more of being neutral. Won’t be enough for any basshead, but shouldn’t feel lacking for everyone else. Mid-range has decent texture with a semi-sweet vocal that isn’t too near or too far, staying mainly in line with the bass but does turn slight bright near upper vocal / lower treble and can get *almost* sibilant if you listen to it on high volume. Treble too extends quite well upward with good clarity and spark, but not quite the level of being analytical sounding. Soundstage is pretty good, above average but not among the best. Overall, the new q-JAYS can be said to have a well-rounded sound. Besides the fact that it can get a bit bright on loud volume (though totally fine in low volume), it has a fairly spotless sound with little weakness to speak of.
 
If the brightness mentioned s something that worries you, here is a neat trick – you can cut just a tiny bit of foam (say, from earbuds’ foam pad) and place it inside the laser cut metal filter. It will nicely tame down the brightness and give just a bit more warmth to the presentation. While you will lose just a tiny bit of soundstage, you will also gain a bit more texture and intimacy. Given the little mod is completely reversible, it is very well worth trying. Just be sure the foam you cut should be almost equal size for both side and you can keep adjusting their size until you get the best balance for your own taste.
 

q-JAYS: New vs. Old
 
Last but not least, and perhaps the question on every original q-JAYS users’ mind – is the new and old q-JAYS sound the same? Well, they are similar, but not identical. The overall quality and quality of bass and upper treble is pretty much the same, but the old q-JAYS has a more recessed vocal and lower treble range that gives it a mild V-shaped presentation. In comparison, the new q-JAYS has a vocal and lower treble range that is more in line with bass and upper treble and thus it has somewhat flatter frequency range in listening. That being say, they do still share the same rich and warmish tone in their presentation. All and all, it is more of a gentle improvement rather than any radical change.
 

 
Sum-up
We have seen triple (if not more) drivers IEM offered on the same price range and we have also seen sub-$100 hybrid IEM from China these days – so does the new q-JAYS really stands a chance? If anything, I’ll say JAYS have managed to make the dual driver BA sexy again, and that’s no small feat on its own. Ignoring the driver-number game or the price war from China, I think many will agree that the new q-JAYS is perhaps one of the most refined and well-engineered IEM in a total package that $400 can buy. In other words, while q-JAYS may not be standing as one of the best IEM of its time like the original q-JAYS once did, it is still a relevant IEM of the current market. Kudos to JAYS, It is the proof that form and function can indeed be married in an uncompromised union.
 
Basic measurement can be found here.
 
A thanks to JAYS for the sample.

Originally running a well-known audio DIY forum in China, the company behind the Aune brand has managed to turn itself into a fairly reputable audio brand in recent years, producing mainly PC based desktop Hi-Fi gears. As far as I know, the B1 portable amp that is going to be reviewed here is the company’s first foray into the portable amp market – and not a run-of-the-mill design at that. Not only does it has a fully discrete design, it is also running at Class A configuration. That sound promising on paper, but does it deliver?
 

 
Spec
Recommended Headphone Impedance: 16~300ohm
Size: 65 x 110 x 18mm
Weight: 230g
Typical THD: Less than 0.0008% @ 1 kHz, 600 ohm / -0dB
SNR: More than 124dB @ 600 ohm
Frequency Response: 10Hz ~ 20kHz, +/- 0.15dB
Crosstalk: Less than 110dB @ 1kHz, 600 ohm
Power (Class A): 25mW @ 16 ohm, 50mW @ 32 ohm, 100mW @ 300 ohm
Gain: +5dB / +15dB
Dual Quiescent Current: 20mA / 40mA
 

 

 
Build Quality
To say B1 is ‘well built’ is almost an understatement – it is drop-dead-gorgeous! The aluminium housing is very well machined, smooth to the touch without any sharp corner. Two transparent windows in the belly allow you to peek inside the amp circuit and two faux leather strips on the top that not only look good, but also serves as a cushion for any device you want to strap onto the B1.
 
If there is any real complaint that I have, I’ll say the volume knob is a bit too low profiled / oddly shaped, making it harder to adjust volume, especially when there is two 3.5mm plug next to it. Last but not least – and not really a complaint here but more of a suggestion – as Aune warns that the current switch must not be used when B1 is turned on, I’ll think a more logical choice will be to make the switch even more recessed than it is now so it won’t get accidentally switched by any chance.
 
Battery Life
Aune quotes that B1 has a 10hours play time running on 20mA mode and half that with 40mA mode. I actually get a bit less, probably around 3~4 hours in 40mA, though it really depends on the load as well as the volume. Suffice to say, the battery life isn’t exactly great. Given it is a Class A amp that isn’t known for power efficiency, I guess that much is expected.
 

 

 
Gain, Hiss and EMI
B1 comes with two gain settings: +5db and +15dB. Personally, I’ll think it would have been better with +3dB and +12dB, as the current setting might be too high for sensitive headphone and IEM, getting too loud (or even worst, channel imbalance) with just a small turn of the volume knob. I will even consider a zero or negative gain setting being helpful for those with really sensitive custom IEM.
 
There is almost no hiss to speak of. There is in fact almost no ‘click and pop’ during start up as well. B1 is very well behaved in those regard. There is however some EMI issue. Cell phone interference can be picked up in close proximity, though not particularly loud and therefore not a serious concern.
 
Tech Prelude
So what is Class A - and if it is that good, why didn’t we see more of it? To put it simple: music is in wave form, swing from one end to another and back for a whole 360 degree. A Class A amp is a device that continuously operates the whole 360 degree non-stop. In the process it usually will waste a lot of power and generate a lot of heat, though it is also considered to be better sounding by many. Most of the amp (and mainly the opamp used) in the market however are in Class A-B configuration, where only half the components are active. The active half is where the signal is, and the inactive half only switches on when the signal arrives. It is far more efficient than Class A, but has its own problems - namely more distortion as components are switched on and off all the time and signal gets distorted when traveling from one end to the other. But at the end, Class A-B is usually the choice for portable gears due to practicality, as the distortion really isn’t bad enough to outweigh the benefit of less heat and much longer battery life.
 
Being full discrete means there is no integrated circuitry in the signal path. It is just another way of saying no opamp but rather individual discrete components (resistors, caps, transistors, etc) is used for amplification. B1 isn’t the first full discrete portable amp I have seen and this kind of implementation does require a lot of attention to detail, especially on parts matching, to show how good it is. A really well implementation can really sound exquisite, just as good as any top tier opamp based portable amp.
 

 
Sound Quality
As usually, my SQ assessment starts with an RMAA measurement, and the result is pretty good. No issue can be seen and the number match up with my reference O2 nicely, which is a very good sign. In fact, B1 outperforms O2 noticeably on stereo crosstalk, no doubt thanks to its dual-mono discrete circuitry that keeps the left and right channel further apart than what opamp usually does. However, the result on current output as well as output impedance is really less than stellar. First, the output impedance is rather high - measured and calculated to about 10 ohm, which is no good news for multi-drivers IEM. Second, current output is fairly low. Aune listed B1’s output power of 25mW @ 16ohm is quite low for a portable amp, and my measurement pretty much confirm it. In contrast, a FiiO E06 can pump out 4 times more power on the same load. One thing I noticed is that B1 @ 20mA mode begins to clip when I pushed the volume too high (regardless of gain setting) during my RMAA measurement (*with a 47ohm load). This is independent of the input volume so my guess is that it is running out of current to remain in Class A at such a high volume, as the clipping on high volume disappears once I retest it on 40mA mode. From both the prospective of SQ as well as battery life, I think easy-to-drive load probably can stay happy with 20mA mode, but anything more demanding should perform better in 40mA mode, though battery life will be cut short. Regardless, both modes don’t really have a lot of current output to speak of. In my opinion, this is very likely the inherent issue of being Class A – trying to push for higher output and you will end up with a portable heater that doesn’t run for very long; trying to keep everything reasonable and the output power will be limited, as in the case of B1. Technically speaking though, I think B1 is better suited for higher impedance headphone rather than lower one.
 

 

 
Subjectively, B1 sounds really good, as good as any top-tier portable amp I have heard. It also sounds rather clean and neutral, pretty much comparable to my reference O2 for that matter. While still very clean sounding, the mid does sound slightly more hollow in 20mA mode, giving the illusion of extra airiness and a bass kick that is stronger than it ought to be, which can be interpreted as being more powerful than the amp is capable of, though not really the case as I find the texture on the midrange, especially vocal, incomplete. Bass note, while has a good kick to it, does sound thinner than it should. Everything however snaps back to normal once switched to 40mA mode – the vocal is restored and all elements are inline again, though no more ‘extra’ airiness. But I don’t consider that a loss as B1 already has a really excellent soundstage and imaging. It makes a pair of flat sounding ER4S feel almost like surround sound, and that’s a wonder of its own and pretty much the best soundstage I have ever heard on a portable amp that doesn’t have any EQ enhancement. Despite not having a lot of power in measurement, B1 doesn’t sound like it is lacking power in 40mA mode. It is not the tightest in control, but it doesn’t sound loose either. All and all, it holds up quite well
 

Size Comparison (from left): FiiO E12DIY, Aune B1, and Leckerton Audio UHA-4
 
Sum-up
I really like B1. It is well built and it sounds great – if it isn’t for multi-driver / very low impedance headphone and IEM, I have no problem recommending it. Aune took on the challenge to manufacture a Class A full discrete portable amp and they almost able to knock it out of the ballpark. Sure, there are still a few kinks here and there – but for as good as it is, Aune really deserves some credit. It isn’t the portable amp for every occasions – but where it does work, it works really well.
 
This review is part of Aune Worldwide Review Tour:
http://www.head-fi.org/t/765999/aune-b1-headphone-amp-worldwide-review-tour-reviewers-wanted

Brainwavz needs no introduction. They have been in the IEM market long enough that they have made a name for themselves, especially in the bang-for-bucks section. The S5 has been in the market for a while now, and the price has dropped from the initial US$130 to the current US$100. However, the price tag is still right in the ‘warzone’ as far as IEM goes, where many competitors coming from China are all trying to outdo each other for being the next budget giant killer. So how does S5 fair?
 

 

 
Spec
Drivers: 10mm Dynamic
Rated Impedance: 16 Ω
Frequency Response: 18Hz ˜ 24kHz
Sensitivity: 110 dB @ 1 mW
Rated Input Power: 20mW
Maximum Input Power: 40mW
Cable: 1.3m, Flat Y-Cord OFC
Plug: 3.5mm Gold Plated Stereo
 

 
Packaging, Accessories and Build Quality
S5 is beautifully packaged. Then again, I won’t expect anything less from Brainwavz with their outstanding track record. Of course they didn’t skip on accessories as well. You will get a pair of Comply foam tip, a pair of tri-flanges eartips, a pair of bi-flanges eartips, 2 set (S, M, L of a total of 6 pairs) of single flange eartips with slightly different design and material. There is also a good looking hard case as well as a 3.5mm-to-6.4mm stereo adapter. All and all, they really give the S5 a premier feel.
 

 
Build quality is top notch as well. The IEM itself is pretty much over-built like a tank, with flat cable, adequate strain relief and overall attention to detail. Though flat cable probably isn’t going to be everyone’s favourite, the over-the-ear design does make the cable much more tolerable in actual use than in a straight-down configuration. I just hope that they had used a narrower flat cable, then it might better appeal to those who really just don’t like flat cable. One area I do want to give credit to the flat cable is that it is hard to get it tangled.  There is also no real driver flex to speak of, which is a good improvement over previous Brainwavz models that tend to suffer from some degree of mild driver flex issue from time to time.
 

 
Sound Quality
Sound signature wise, S5 is probably best described as U-shaped with good presence on both ends of the frequency response. Bass has very good depth, rumble, texture and quantity - enough to satisfy bass head but still in a well-controlled way that it won’t offend those who don’t particularly enjoy bass. Mid-range however is a little bland – not bad per se, but doesn’t have much to praise of either. Treble has good extension, clarity and crispiness, but the lower treble / upper vocal range has some noticeable peaks that can become rather edgy when the volume is pushed too loud. Soundstage is quite good, might not be the best but definitely well above average.
 

*Compensated. Measurement accuracy is not guaranteed

*Measurement accuracy is not guaranteed
 
All and all, the graininess on upper vocal is probably the only real weakness as it makes S5 more appealing to those who like brightness in their music. Tuned that down a bit, maybe by the use of foam tips or extra filter / acoustic dampening, and S5 will shine.
 

 
Sum-up
There are some really great sounding IEM coming out of China these days on incredible low price, enough to rewrite everything we know about the ratio of price vs. performance. While S5 won’t win the price war these days, it is still a very solid offering on its own right. As I imagine, Grado fans who usually don’t mind a bit of brightness will probably also enjoy this IEM with their Rock music.
 
A thanks to Brainwavz for the sample.

Echobox is a new startup with a strong audiophile’s background, and the Finder X1 is the company’s first IEM that has placed an emphasis on durability as much as it is on sound quality. The company has already finished up a successfully indiegogo campaign that offered the early bird Finder X1 for US$79, though you can still get one at US$149 with a January delivery day before it will be eventually sold at its regular price of US$199.
 

 
Spec
Driver: 9.2mm dynamic driver with PEEK diaphragm
Frequency Response: 15Hz ~ 35kHz
Sensitivity: 96dB/mW
Impedance: 22ohm
THD: under 1%
Housing: Titanium
Plug: 3.5mm Stereo Gold Plated
Cable: 1.2m Silver Plated Copper
Sound Tuning Filter: Reference, Bass and Treble.
 

 

 
Packaging, Accessories and Build Quality
The Finder X1 I have with me is probably the same as the early bird perk, so there might be a little different form the final retail version as far as packaging goes. But if the early bird packaging is of any indication to the level of attention that Echobox has put into its product, I can only guess the retail packaging will only get better as it certainly doesn’t look anything short of a high-quality, retail-ready product. However, as much as I am impressed with what I have seen, there are still one minor flaws – the sound tuning filters are so tightly fitted into the box that I have a really hard time getting them out. Also, it would have been nice to have a small case or holder to put those filters in once they are taken out of the box. While the included hard case is really good in quality, it doesn’t have the right compartment to place the 4 tiny filters in by themselves as they can fall out quite easily. This might come as a slight inconvenience for those who like to re-tune their Finder X1 from time to time as you might have to find your own way to secure those filter in the hard case.
 
Accessories wise, besides the filters and hard case I have mentioned, you will also find a couple pairs of single flange silicone eartips of different size and two pair of tri-flanges of different size. For the retail version, there should be some Comply foam tips included as well. All and all, a fairly good selection of accessories, though nothing above and beyond.
 
Build quality is where the Finder X1 excels – well, mostly. Echobox has made a point that the Finder X1’s housing is made out of titanium for increased durability, but I will say that the finishing is quite beautiful as well. As an added bonus, it is also extremely light. The cable is also equally good in quality and look – so why is it not the perfect IEM? Firstly, because of the bell shape design small housing and the lack of cable’s strain relief, it is actually not that easiest shape to grab when you are trying to remove it from your ears (and make worst if it sits deeper in a larger ear canal). That tends to encourage user to grab onto the cable to remove the earpiece – while the cable is really good in quality, no doubt all the pulling still won’t be great in the long run. Also noticeable is that the single flange eartips, while excellent in build quality, could use a small opening on its nozzle as the current design isn’t the most optimum for smaller ears. Lastly, I notice the reference (black) filter doesn’t screw all the way down like the bass and treble filter. Though it doesn’t impair its functionality (and you won’t be able to see it under the eartips anyway), it does mean the reference filter is slightly easier to unscrew than the others. None of the above is really much of a turndown, so to speak, as the overall build quality remains excellent and these issues can be overcome with either careful use or aftermarket parts. But in a sense, it is still a little bit form over function.
 

 

 
Sound Quality
As far as sound signature goes, the Finder X1 has a mild U-shaped sound with a bright upper tone. Bass extends fairly deep, but lacks a bit of body and weight to really have a character of its own. It won’t be a bass head’s dream-come-true, so to speak, but otherwise there is no real fault to speak of either. It is clean, well behaved and overall in good quality. Mid is rather on the dry side, as you would have expected from a mild U-shaped sound signature. As a result, vocal sounds just a bit too far - not entirely lifeless but it does leave the listener wanting for more. Treble on the other hand is both the highlight and perhaps the Achilles’ heel of Finder X1, and this is where the tuning filters have the most effect. On the default reference filter, the treble is crisp, airy and beautifully extended on the top, but comes up almost edgy near the upper mid / lower treble range and can be somewhat irritating on my normal listening volume. The treble filter just worsen the edginess a bit more and as a result, I didn’t quite spend any real time on it. The good news is the bass filter does tame the treble down enough that I can more comfortably listen to the Finder X1 for an extended period of time, provided if I don’t push the volume too high, which will bring the edginess back again. The downside is however, the bass filter does take always some of the crispiness and airiness in exchange. Due to the mild U-shaped sound and the well extended treble, soundstage is excellent on the reference and treble filter. Even with the bass filter, which reduces the airiness a bit, it is still well above average.
 

 
Sum-up
As Echobox first IEM, the Finder X1 speaks quality – both sonically as well as aesthetically. If you already got the early bird US$79 deal, I’ll congratulate you for getting a lot of IEM for quite a small price. Even If you are on the January deal of US$149, it is still a good bargain overall. The final retail price of $199 however will definitely put Finder X1 in stiffer competition since that is the same space where some of the best value / performance IEM occupy. So if you are already planning on getting a pair, do it before it is too late – of course, I do want to put the emphasis that the Finder X1 is not for everyone – just make sure you do like a mild U-shaped sound with a bit of brightness. I can imagine music like EDM and string instrument will go particularly well with the Finder X1’s clean and slightly sterile presentation.
 
If ever Exhobox could give the Finder X1 is bit more warmth and a bit less treble, it could very well have a big winner at hand. While Finder X1 is not perfect, it is still stellar as a first effort into the very crowded IEM market.
 
A thanks to Echobox for the review sample.

Build Quality: For something hand built, the overall build quality is quite good. Of course, it isn’t nearly as perfect as something from a plastic molding machine but it is far ahead from the early days of DIY cable with ugly and stiff heat shrink. The actual cable itself is surprisingly slim and flexible, almost looks fragile in a way but thankfully it is quite strong in the hand. The transparent sleeve showcases the rather delicate braiding of 8 silver plated 5N OFC wires. Yet because of the slimness of the individual wires, the whole cable is still extremely soft and thin. The pins termination as well as the Y-splitter section are all pre-molded plastic parts glued together to cover up the splitting and solder joints. The Yarbo 3.5mm plug is slightly on the heavy side but rather good in build quality. Inside, the solder joints has been hot glued to improve durability and strain relief is created by layering multiple heat shrink together. Again, not as good looking as actual molded strain relief but it is functional to say the least.
 

 

 

 

 
Ergonomics: Instead of memory wire, the ear loops are pre-molded using heat shrink. Due to the great flexibility and thinness of the cable, the overall ergonomics is excellent. Probably one of the best I have even seen among removable cable, stock or custom.
 
Tangle + Memory Effect: While the cable is soft, it does have a little springiness inside and tends to want to straighten itself instead of trying to curve up even after long storage time inside tight space. So basically it is quite a tangle- and memory-free cable
 
Microphonics: Fairly low in microphonics, almost as low as the stock UE cable for TF10 and much less than the stock cable on Lear LCM-5.
 
Overall: The cable itself has good build quality and excellent ergonomics. The price is also pretty good – well worth the asking price in my opinion because it almost disappears during use. I don’t think you can ask more than that.
 

I reviewed the BL-2 from Tube Amp a while ago. It is a portable tube amp that is on the cleaner side of the presentation, which is quite different from the warmish, mellow sound that you would have expected from tube gear. Nevertheless, it is still an excellent sounding amp on its own. Now the company has released another portable amp to the market, the TA-1. What is unique about the TA-1 is that it is a full discrete amp - meaning instead of using fully integrated opamp, the circuit is composed mainly of individual transistors, resistors and caps. Priced around US$210 in China, TA-1 can be found between US$230~$250 outside of China.
 

 
Spec
Input Sensitivity: 220mV
Rated Output Power: 2 x 450mW
Frequency Response: 20Hz – 80kHz (-1dB)
THD: Less than 0.001% (1kHz, 2.5V)
SNR: More than 106dB
Recommended Headphone Impedance: 16 ~ 300ohm
Battery Life: Over 10 hours
Weight: 250g
Size: 110 x 70 x 25mm
 

 

 
Accessories and Build Quality
Unlike the BL-2 which has a more luxurious pleather box, the TA-1 comes only in white hard paper box. Inside, there are only the charger and a short, though good quality 3.5mm interconnecting cable. The charger, which is the same from BL-2, pumps out 13.8V. That means you have to carry it around when travelling in order to recharge the amp. The good news are that TA-1 runs much longer than BL-2 (10+hrs vs. 3.5hrs) and much colder. So travelling is much less an issue, even though the two share the same large housing and about the same weight.
 
Build quality is on par with its elder sibling the BL-2: solid, tank-like, and definitely not flashy or eye catching. As mentioned earlier, one of the main selling points of the TA-1 is its full discrete topology. You won’t find an opamp anyway in the circuit. As far as I know, there is only one other commercially available portable amp that employs a full discrete headphone amp circuit and it is the Audio-gd NFB-16. But given NFB-16 has the size of a small desktop amp (and larger than four TA-1 together), it is really hard to classify it as portable except for the fact that it does operate on battery.
 

 

 
Gain, EMI and Hiss
Maximum gain is at an exceedingly high +22.5dB, which is probably more suitable for slightly inefficient full size rather than overly sensitive IEM as you might not get pass 9 o’clock on the volume pot most of the time. We have seen the same issue on the BL-2 but at least BL-2 is lower in overall gain (+19dB). I really wish Tube Amp can implement a gain switch as given the majority of headphone out there don’t really need that much gain.
 
EMI is decent - audible but low enough not to be annoying or get into the way. There is a very faint hiss that is inaudible to most except for the most sensitive of IEM. Oddly enough that this very faint hiss will go away once the volume increases (*generally it is the opposite that happens), which I guess is a good thing.
 

 

Size comparison (from left): FireStone FireyeHD, FiiO E12, TA-1, Leckerton Audio UHA-4, BL-2.
 
Sound Quality
Let starts with some of the more objective aspects of the TA-1. First, the amp measured fairly flat on RMAA. It has a very slight incline going upward but it is so small (0.1~0.2dB) that it should be inaudible. There is a mild roll-off starting from 100Hz and slowly down to -1dB @ 20Hz, which means it is close to inaudible as well. Noise and dynamic range are good as well, but THD and IMD are on the higher side – still below 0.2% but considerably higher than the reference 0.02% of O2. Output impedance is measured to a decent 2~2.5ohm, and should be fine with most low impedance headphone. Output current is quite good and nothing to complain about.
 

 
Subjectively, and if I have to sum up TA-1’s sound in just one sentence – it is a tube sounding amp without a tube. That is of course made more interesting to the fact that BL-2, the TA-1 elder sibling, does have a tube inside but is probably too clean sounding to be associated as tube amp in a blind test. But TA-1 is by no mean a step down. In fact, I am personally much preferring TA-1 over BL-2 even though BL-2 is an excellent sounding on its own right. Volume matched and compared to an O2, it is obvious TA-1 comes out just a faction slower in transient. Music note is not quite as sharp, clean or as aggressive. There are however much more underlying texture on the TA-1 that fills up the space, much more so than BL-2. The same texture can also be found on O2, but mostly fainted away, hiding in the background between the instruments. TA-1 in contrast will enrich this background information in a subtle way and brings them forward without any twisting and obvious coloration. It works out almost the same way as how a vacuum tube amp will add to the richness of the music without being protrusive, an effect similar to what I have heard recently on the iFi Audio iTube. Because of the mellow and euphonic nature of the presentation, TA-1’s soundstage doesn’t come out quite as wide and well defined as O2. It is not small per se either – it is just that there is some much texture in between, that soundstage tends not to stand out as particularly important aspect. In a way, it is more about being immersive rather than pinpoint accurate when it comes to how it handles image and positioning.
 

TA-1 (left) and BL-2 (right)
 

The inner-working
 
In Sum…
All and all, TA-1 comes close as a top-tier / near top-tier portable amp. Technically it is not as tight as a true top-tier amp that is designed purely from measurement. But it is not sounding so colored that it is hard to enjoyable either, at least not to the casual users who are not strictly limiting themselves to the most transparent of gears. If anything, TA-1 strikes a good balance being musical, if not euphonic sounding while staying relatively neutral – obviously, it is not going to appeal to purists who are seeking a wire-with-gain solution. If you are however interested but still not totally sure about having a portable tube amp, then TA-1 will definitely be quite a good alternative to consider.
 
A thank to Tube Amp for the sample.
 
[UPDATE] The TA-1 reviewed here is the original/older batch. The newer batch, which I have not heard, is said to come with 10% lower gain and less imbalance in lower volume so it will go better with sensitive IEM.

The Korean company really needs no introduction at this point. They have proven themselves as a capable IEM maker with a series of top of the line hybrid as well as some good sound yet budget friendly dynamic IEM. The new Altone 200 is the continuation of the company’s hybrid line of IEM, with a never-heard-of price point nonetheless. The best part? You are not getting lesser of SQ just because you are paying a cheap price.
 

 
Spec
Driver Units: Knowles' TWFK Double Balanced Armature + 8.0mm Single Dynamic Unit
Impedance: 22 ohm @ 1 kHz
Sensitivity: 105 dB @ 1 kHz
Power: 100 mW (Max)
Frequency Response: 20 Hz ~ 20 kHz
Connector: 3.5 mm / 24 K Gold coated L-Type Plug
Cord: PVC Round 1.2 M / Y-Type
Weight: 24 g
MSRP: USD$145 + USD$20 EMS Shipping
 

 
Packaging, Accessories and Build Quality
Since you are not getting lesser of a SQ, something else will have to give. In this case, the packaging is definitely not quite matching what the IEM can do. Same can be said to the accessories department as well. All you’ll get are the fairly basic silicone eartips of various size, a soft case, a pair of foam and a shirt clip. Not nearly as elaborate as the previous top model we have seen from T-PEOS, but I won’t really complain at this kind of price. The overall design is also simplified, where the removable cable design is, well, removed. But the overall build quality is still very solid, considered that the housing is still mainly made out of stainless steel like much of T-PEOS’s line-up. The good thing about the simplified design is that the earpieces are probably one of the smallest among all triple driver hybrid IEM, which is definitely not a bad thing comfort wise.
 

 
Sound Quality
The sound signature of Altone 200 is warm and slightly sweet with very mild U-shaped frequency response. Bass reaches down deep, with just a small touch of rumble and quantity enough for most except for the most hardcore of basshead. Mid range is just a tab recessed compared to bass, though still retains quite a good amount of sweetness and texture while at the same time places the vocal just far enough to give good spaciousness but not enough to distance it from the listener. Treble reaches up quite well, but the upper extension is just a tab smooth and some of the top-end sparkle is missing. However, it still retains enough detail that you will almost never notice any missing of detail unless you are just switching from a bright and analytical set of headphone. Soundstage is fair. If its older brother the H-200 has a 3^rd row seat in a theatre, I reckon Altone 200 is more like a 2^nd row seat. It is not right in the face but you can certainly still feel the intimacy.
 
For the most part, the new Altone 200 is different from the older model (i.e. H-100 and H-200) in the sense that it exhibits the least ‘grand and open’ of a presentation, but not in a bad way. It is more upfront and intimate, and you probably won’t notice it as a 3 ways hybrid if you were not told. Those who don’t like the T-PEOS’ more V-shaped and opened sound in the past will more likely going to find Altone 200 enjoyable while those who do like the old sound signature shouldn’t feel abandoned either. While Altone 200 does have a more versatile sound signature that should better suited for different listening style and genre of music, the difference however doesn’t make Altone 200 a vastly better or worst sounding IEM when compared to the older flagship H-200. As with most IEM of this high calibre, you are really just looking (or listening, to be more precise) for the minute difference in presentation and how it fits to your taste rather than flaws in pure technical sense. It is more of an evolution of tuning, as opposed to a revolution of sound quality.
 

 
Sum-up
T-PEOS has made top quality IEM in the past, and continues so with the new Altone 200 – no surprise there. The true smasher here is however on the price. With a fraction of its competitors’ price, you are getting a tremendous amount of bang-for-the-bucks with an IEM that can compete in the top-tiers’ category. That’s, in every sense of the word, budget Hi-Fi at its best.
 
A thanks to T-PEOS for the review sample.

DQSM is by no mean a prolific brand when it comes to releasing new product. Instead, it like to take its time and get things right. Its previous flagship, the Turandot, released back in 2019, is still in many ways a front runner in the current earbuds market with its unique euphonic and musical presentation. This time around however, DQSM has decided to tune its next flagship earbud, the PD21, with a different signature - one that focuses more on technicality.

Intended to be wore over the ear, PD21 comes in two flavors: 2 strands and 4 strands twisted cable (and also option of single-ended 3.5mm or balanced 4.4mm plug). While the 2 strands version is already impressive on its own, I do recommend the 4 strands version first if your budget allows, as it really ‘correct’ some of the minor shortcoming of the 2 strands version. In fact, PD21 was first originally released only as 2 strands but it was the early customer’s feedback that pushed DQSM to release the 4 strands version. So what’s the difference? Well, there is a very very minor harshness / brightness in the upper vocal of the 2 strands version that is smoothed out in the 4 strands version, making it almost as flawless as it can be. Do however note that PD21 comes with MMCX socket so you can experiment with different third-party cable if that’s your fancy, though personally I think the cable on the 4 strands version is already superb in every way and doesn’t really need replacing.

As said, while PD21 is the new flagship, it is not a direct upgrade of Turandot as far as sound signature goes. PD21 spots a more balanced and neutral sound that is technically better than Turandot in many ways - crisp and analytical on the treble and well extended on bass, with a big soundstage no less. There is almost no obvious flaw or shortcoming in the presentation to speak of. Perhaps the only thing PD21 isn’t quite as good as Turandot is that it doesn’t quite have the kind of euphonic quality in its mid-range that Turandot is great for. I’ll say instead of which is better in an absolute sense, they are more like compliment of each other with different style of tuning. Turandot really shines with vocal, where PD21 is versatile on all genre of music.

All and all, another excellent ToTL earbud from DSQM.

First, I’ll like to thank Spider Cable for the sample. Spider Cable is a relatively small company in the mighty competitive cable market, but they don’t intend to stop at just the cable market. As their first IEM, realvoice is special in the way that it is intentionally tuned to maximize vocal performance, or should I say, to capture the emotion in the singer’s voice. Costing only about US$90, this unique IEM has became one of my favorite in the sub-$100 category.
 

 

Unfortunately the sampling CD isn't included due to international copyright issue.
 
Spec
Driver: Dynamic Driver 12.5mm
Impedance: 18 ohms
Frequency Response: 5Hz~20000Hz
Sensitivity: 107dB
Cord Length: 120cm
 

 

 

 
Packaging, Accessories and Build Quality
The IEM comes in a well printed paper box. Nothing very fancy and just a little thin for my taste, but overall up to the task.  For accessories, there is a shirt clip, four pairs of single flange eartips (XS, S, M, L), one pair of small’ish bi-flanges eartips, a zipped hard case and a backpack clip to use with the hard case. Overall, the accessories are very well made. For those who have the older package, you might only have three pair of single flange eartips in the package (mainly the XS, S, and L). You can email Spider for extra free pair of middle side eartips. While the eartips are decent, I rather prefer using alternative single flange with a wider nozzle opening (i.e. MEElec single flange) to improve the detail and openness over the stock narrow eartips. Build quality is quite decent, especially on the metal earpieces. It is heavier and larger than other IEM with side mounted transducer in my collection, but it is surprisingly comfortable and doesn’t feel awkward in use, just don’t run with it. What is less impressive however is the slightly thin cable from the Y-splitter up to the earpiece. It could use a slightly thicker cable and perhaps better strain relief as well. The iPhone / iPod compatible mic+remote has an uncommon design though I find no problem with it. Microphonics is below average. Isolation is quite good. Not the best around but more than enough to handle anything but the noisiest environment.
 

 

 
Sound Quality
The IEM has been given at least 50 hours of burn-in before the review. Not major sonic change was detected.
 
The sound signature of the realvoice is very warm, sweet, relaxing yet not laid back and with a smooth upper end. Bass hits hard and has a full body. It can get slightly boomy at time which results in texture lost, but overall it remains in relatively good control and doesn’t become muddy. Mid is the strength of the overall presentation, pairing well with the bass but not overly done. It is warm to almost lush, sweet, intimate, well textured but not excessively up-front. It feels like the singer is right there with you, but not singing into your face or become overly vocal dominance that drowns out the small detail. Treble has sparkle, but small in amount and takes a step back in the overall presentation. It rolls off just a bit too early at 15kHz, but the lower end of the treble is able to maintain just enough micro detail not to feel overly smooth or totally lacking. However, the lack of upper extension translates to the damping of transparency and air. Because of that, soundstage is a little below average, which is not something uncommon for a very vocal centric sound.
 

The side-mounted IEM gathering - Spider realvoice, Radius DDM and Sony MDR-EX700.
 
Coloration is really the key with realvoice. While there are other IEM in the same price range that are technically better (i.e. Sunrise Xcape-IE, a few of the HifiMan), or even a few that also do vocal quite well (Sherwood SE-777, MEElectronics A151), the realvoice is really able to standout on its own by offering a distinct vocal that is relaxing, warm-and-fuzzy to a point of almost euphonic. It is the kind of IEM that wants you to listen to the music instead of listen to the IEM – and realvoice is doing a good job at that.
 

 
Verdict
While it might not be one-size-fits-all regarding genre versatility, Spider has made the right decision to make the realvoice shines at what it is good at. Combining good build quality, comfort on the fit and one of the best vocal performances under $100, the realvoice is certainly quite a bargain and an easy recommendation for vocal lovers. With news of a no-mic version going to be released in the near future at an even lower price, I have a feeling that we might have a Sonic Diamond in the making.

Yincrow is no stranger to higher end earbuds. They first set the bar high with the original RW-1000 in 2019, then followed with a flagship challenger RW-2000 a year later. Now, they released another upgrade of the RW series, the RW-3000, aiming for the crown of the earbuds’ market.

RW-3000 pretty much retains mostly the same signature housing design element as RW series from previous years – based the same titanium alloy but with a fancier design and actually just a tiny bit smaller in size. All and all, it results in an lighter housing that is equally (if not more) comfortable in use. It still comes with more or less the same type of 4 cores braided silver wrapped single crystal copper wire like RW-2000 but in a different color combo and cryogenically treated. The true upgrade is however really in its heart – with a new dynamic driver with 4 layers fused high molecule diaphragm.

Spec
Driver: 15mm
Sensitivity: 113dB/mW
Impedance: 16 ohms
Frequency Response: 10Hz ~ 40kHz
Distortion: <1%
Channel Matching: <1dB
Rated Power 5mW
Max Power: 20mW


RW-3000 (left) vs RW-2000 (right)

The first thought that comes to my mind when trying to describe RW-3000 is the word ‘balanced’ – Yincrow has been tweaking / crafting its own sound signature since RW-1000 with its various reversions to try and find a compromise between technically strong vs musically pleasing. RW-2000 is where they find the middle ground, and RW-3000 is where they make it grand. You will find RW-3000 follows the same warmish sound signature from RW-2000, with a much bigger soundstage and better extension on both ends. The result is a sound that is well tuned and balanced, versatile on all genre and doesn’t bias toward any particular frequency. I won’t call it flawless per se, but certainly it doesn’t have any obvious weakness to speak of. It is what you will expect from a ToTL earbuds

Perhaps the only obvious issue - especially for those of who are familiar with the earbuds market and perhaps own the RW-2000, is that RW-3000 isn’t cheap - priced pretty close to the upper end of what you would expect from a ToTL earbuds these days. Given the level of performance and build quality, the price is still justifiable, thought certainly not quite as high in price/performance ratio as the previous RW models. The only thing I’ll ask is that instead of offering different version of termination (*3.5mm single-ended, 2.5mm Balanced and 4.4mm balanced), they could have just included an exchangeable plug with all the different tips, such as what FiiO had done on their EM5. That would have really perfected the whole package.

p/s: if you wonder why the tile said 'Holy Cow' - it is because Yincrow always adopts an bovine nickname in Chinese for the RW series. RW-1000 is 大牛 (= big cattle), RW-2000 is 野牛 (= bison) and RW-3000 is 天牛 （= heavenly cow). So holy cow?

The name Massdrop is a well-known and has been fairly well-received by us HFer - while the company doesn't exclusively deal with audio gears, it has however brought us quite a few of really excellent audio products as well as collaborations from various audio companies - from well known huge international brands to lesser known small businesses that might otherwise hard or expensive to find for many whom don't live on certain part of the world. The community driven company has however just changed and simplified its name to 'Drop', and the NuForce MOVE true wireless (*TWS = True Wireless Stereo) IEM will be the first product that come with the new branding.

A big thanks to Drop for sending me a pre-production MOVE for an honest review - it is currently still in pre-order phase (during writing) and you can get more detail here: https://drop.com/buy/drop-nuforce-move-wireless-in-ear-monitors



SPEC
Driver: Knowles balanced armature
Bluetooth: BT5.0 with HSP v1.2, HFP v1.7, A2DP v1.3, AVRCP v1.6
Codecs: SBC, AAC
Wireless range: Up to 33 ft (10 m)
Frequency response: 20 Hz–20 kHz
Impedance: 22 ohms
Sensitivity: 105 dB +/- 3 dB at 1 kHz
Microphone sensitivity: -38 dB +/- 3 dB
IEM waterproof rating: IPX5
Charging: USB-C
Battery life: 24 hrs total (6 hrs + 3 full charges—18 hours—from charging case)
Weight of IEMs: 0.4 oz (10 g)
Weight of charging case: 1.9 oz (53 g)





As far as the overall design and spec goes, there is really nothing that stands out particularly with the MOVE - which is kind of a good thing as far as TWS IEM is concerned. I have a pair of Purdio AirOn by Odoyo from the early days of TWS back in 2017 - the shape of the earpieces really leaves a lot to be desire and certainly the early version of TWS isn't performing nearly as good as I hope it can be - these issues are of course not unique to the AirOn but also fairly common among early TWS IEM. Many of these early TWS IEM were trying to make their shell as small as possible, and thus ending up having odd angle and shape on the nozzle, not to mention many of them use super small, for TWS only eartips. The combination of them both make my AirOn rather uncomfortable in any extended period of use and I can't change the eartips to something better as common eartips will not fit into the tight fitting charging case. Keeping the AirOn and its early version of TWS all sync up can also be challenging, especially if you are not in the most ideal of environment (*minimum interference from other wireless communication, such as WiFi and other BT devices). Music is generally fine but watching video is mostly out of the question due to really bad latency. Of course the current 2nd generation of TWS, such as the one in MOVE, has mostly conquered these issues. First, the shape of the MOVE makes more ergonomical sense as it resembles what a normal IEM will look like. Secondly, the nozzle as well as the charging case can take a normal eartips - in fact, I am using SpinFit on mine and it fits into the case just fine while adding extra comfort in use. The included eartips are fine to use by the way, but extra option is never a bad thing when it comes to fit on an IEM. Lastly, like many of the the new generation of TWS, the two side of the MOVE can sync up fast enough that watching YouTube is actually no longer a nightmarish experience. However, do note that under really heavy wireless interference, the MOVE will still have syncing issue. I was in a hospital's side hall the other days waiting for a check up and I was having sync issue with MOVE - It was a small waiting area with a lot of computers and medical equipment, and probably over a dozen smartphones mostly trying to stream video and music. So, if you are planning to use a Bluetooth headset in similarly noisy (*wireless wise) environment, TWS might not be the best choice. Otherwise, I generally have no issue with using MOVE around the house and in the city, for music, video as well as taking calls.




Last by not least, the face plate of both earpiece on the MOVE are each a single button, and can be use for some basic remote control - for example, pressing the right side for 2 seconds is volume up, the left side for 2s is volume down. You can also play / pause / forward / backward / take call / on / off / voice assistant / paring using various combination of press and holding time. I won't bother you with detail but I do want to make note that the earpieces will automatically turn off when put back into the charging case. Likewise, they will turn themselves on when they are taken out - therefore there isn't any real need to manually turn the MOVE off by pressing the bottom. You can just put them back into the case when you are done and take them out when you need them. One extra note, putting the earpieces with flat battery into the charging case for 15 minutes should give them enough juice for more than an hours. The battery in the earpieces is rated for 6hrs use, which I have not fully tested as I rarely use an IEM for that long continuously, and every time I put the earpieces back into the case they just top themselves up. As such I barely able to drain them more than 70% before I went home and able to charge them all up with an USB adapter again.

Sound Quality
The overall sound signature of the MOVE is on the slightly warm and smooth side of things (*FR curve is available on the product link above). I'll personally say it is comparable to most entry level wired IEM under $100 - not a giant killer per se but I don't detect any noticeable shortcoming either. It is overall an enjoyable sound that ever so slightly on the fun side, going well for most genre of music but perhaps not analytical or specious enough for instrumental or classical. The single BA driver from Knowles was surprisingly full sounding, which reminds me more of a dynamic driver rather than a balanced armature. In fact, I thought it was a dynamic driver for the first few day of use as I didn't read the online product page carefully at first when I received the MOVE and the pre-production unit didn't come with any document. In any case, I reckon a full sounding BA is not a bad thing at all.

With the MOVE, we are stuck between SBC and AAC as the two main BT codec. Of course, if you are using an Apple products, these are the only two codec you can use anyway. For Android smartphone with Oreo (8.0) and up, AAC codec will be used, otherwise it is SBC. I would have love to see aptX being supported as well, but whether or not it will be beneficial to SQ is less clear cut. Studies and measurement have shown that, while aptX is definitely better at high bandwidth situation (*single device, minimum wireless interference), it can be outperformed by SBC in low bandwidth situation (such as noisy or a TWS situation) as the higher compression and transmission rate on aptX might end up creating more artifact than SBC. Of course, there is also the issue of cost on implementing aptX as it might require better chipset, bigger battery and licensing from Qualcomm. For those who are on Android, you can tweak your BT setting slightly if you enable the developer setting. For me, my smartphone uses AAC codec with MOVE most of the time and I didn't really notice any particularly ill effect when streaming music and video since AAC is kind of a mid-point between SBC and aptX. At the end, TWS is a product of convenience at its heart - if you really demand the best of SQ, then higher end BT adapter like the FiiO BTR3 or EarStudio ES100 are probably more suitable than a TWS setup. Perhaps with future BT chipset release we might finally have a TWS setup that can address all the remaining issues of the current generation.



Summery
As an early TWS adopter with the Purdio AirOn, I actually never really warmed up to it due to its shortcomings, many of which are common among TWS of its time. The 2nd generation TWS like the MOVE on the other hand has finally delivered most of what TWS has promised - with balance between decent SQ and actual usability. There are tons of cheap TWS IEM coming out of China these days as well as a handful of more expensive options from the usual big brands. The MOVE is nicely slotted between them as a solid choice with a likable sound and a practical design. With its current pre-order price, it actually comes out cheaper than how much I have paid for my Purdio AirOn some 2 years ago, so what's there not to recommend? It should definitely be in your shortlist if you are looking into a TWS setup for everyday use.

You probably already know OPPO as a smartphone brand, but the company called OPPO Digital isn’t exactly the same. It is the American sister company of the Chinese smartphone company, and its main business is Blu-ray player. Recent years however, the company also begins to develop a series of personal audio products including desktop headphone amp and a few planar magnetic headphones, which are very well received by the audiophiles’ community. The HA-2 we are going to look at is the company’s first portable amp + DAC and as the title of this article already suggested – quite an outstanding piece of kit.
 

 
Spec
Frequency Response: 20 Hz - 200 kHz
Audio-in Level: 1Vrms
Line-out Level: 1Vrms
Recommended Headphone Impedance: 16 Ohm - 300 Ohm
Maximum Output Power: 300mW @ 16 Ohm, 220mW @ 32 Ohm, 30mW @ 300 Ohm
Headphone-out Output Impedance: 0.5 Ohm
Output: 3.5mm Headphone-out, 3.5mm Line-out
Input:
Analog: 3.5 mm stereo audio-in
Digital:  
USB A for iPod / iPhone / iPad;
USB micro-B for smartphones with USB OTG feature and computers.
DAC Chip: ESS Sabre32 Reference ES9018-K2M
Input Format: Stereo PCM, Stereo DSD (DoP v1.1 or native)
PCM Sampling Frequencies: 44.1 kHz - 384 kHz, 16 / 24 / 32-bit
DSD Sampling Frequencies: 2.8224 MHz (DSD64), 5.6448 MHz (DSD128), 11.2896 MHz (DSD256, native mode only)
Battery type: 3000mAh Li-Po Rechargeable
Battery Life: Approx. 13 hours (Audio-in) or 7 hours (Digital-in)
Dimensions (W x H x D): 2.7 x 5.375 x 0.5 inches, 68 x 137 x 12 mm
Weight: 6.2 oz, 175 grams
 

 

 
Build Quality
Right off the bat, the packaging of HA-2 already screams premier quality. It almost feels like you just got a top-of-the-line smartphone rather than a portable amp+DAC. The actual build quality is of course just as good as what the packaging has suggested. While I already told you that OPPO smartphone and OPPO Digital isn’t the same company, the HA-2 sure looks like it shared some of the smartphone’s gene on how well it is designed and put together. There is no rough corner anywhere and most of the housing is covered in real leather. I have seen and owned some great portable amp and DAC in my life, but HA-2 has the best build quality so far. It is the portable amp+DAC that won’t make you look geeky when it sits next to your smartphone / iPod / iPhone.
 
As far as accessories go, HA-2 comes with just about everything you need to enjoy your music. All you need is to supply the compatible source and a pair of headphone. In the box, you will find the OPPO’s VOOC Flash charger (which is similar but not identical to Qualcomm Quick Charge on how it functions), the VOOC compatible USB cable, two rubber bands, a 3.5mm-to-3.5mm interconnecting cable, a Lightning-to-USB-A OTG cable for Apple devices and a micro-to-micro USB OTG cable for Android device.
 

ABC switch for input: A for iDevice, B for PC and Android, C for analog audio-in.
 

Gain switch, bass boost, and battery button.
 

The 3.5mm analog audio-in socket also double as line-out when used with digital source.
 
Battery Life
The actually battery life is pretty close to the quoted number by OPPO, which is roughly 13 hours as amp only or 7 hours as amp+DAC, gives or takes an hour or so depends on the volume and headphone you used. Battery capacity can be checked by a single quick press to the battery button on the side.
 
A few things to note: First, if you are using an Android smartphone as source and not planning to use the stock micro-to-micro USB cable, you need to find a compatible cable in order to stop HA-2 from draining your smartphone battery. What you want is a bi-directional micro-to-micro USB OTG cable, not a one-way OTG cable (which is an older standard and rarer these days, but you can still find it). Secondly, HA-2 can be used as a power bank to charge your digital source, mainly smartphone and iDevices, by pressing and holding the battery button until the battery LED lights up. You can use this even when you are listening to music on HA-2, which will keep your digital source’s battery top up as much as it can, but also shorten HA-2 battery life noticeably.
 
Gain, Hiss and EMI
There are two gain setting on the side of HA-2. The lower gain setting is actually a negative gain of about -2dB, where the high gain setting is about +8dB. We will discuss further on this in the SQ section.
 
Hiss performance is quite excellent. Even with my hiss prone Shure SE530, there is no noticeable hiss to speak of with maxed out volume on both high and low gain. Same can be said to click and pop performance, which is barely noticeable. EMI performance is also great. The black ground stays pretty much pitch black with no interference from a smartphone receiving call sitting next to it.
 

Size comparison (from left): Sony Xperia Z2, HA-2, FiiO E12A.
 

Sony A10 digitally feeding the HA-2
 
Sound Quality
As usual, we begin with a look into HA-2’s measurement. RMAA shows an impressive result that just about rival my reference iFi iDAC + O2 setup. Frequency response is pretty much flat, as you can see on the FR graph below. While intermodulation distortion is slightly higher in comparison, it is still well within the inaudible range and doesn’t pose any concern. Used as amp+DAC, line-out is about 0.98Vrms, pretty close to the official number of 1Vrms. Headphone-out on the other hand is about 0.77Vrms max in low gain and 2.52Vrms max in high gain. That’s plenty for IEM and sensitive headphone, but might not push enough volume to really demanding big can. Current output is quite good as well. Not the biggest I have ever measured but it is definitely some of the best.
 
As far as I can tell, the gain factor (-2dB and +8dB) doesn’t change when HA-2 is used as amp only, but it might run out of voltage swing and start clipping if the input is too high. For example, with FiiO X5II’s line-out (~1.55Vrms) as well as iFi iDAC (~2Vrms), HA-2’s max headphone-out on high gain can only push to around 3Vrms, or about +6dB. But interesting enough is that even with such a hot input, the headphone-out doesn’t seems to sound distorted when used in lower volume with IEM. That suggests the clipping isn’t happened on the input but on the output stage. So although OPPO only recommend the audio-in to be used with 1Vrms source (Apple?), it seems okay with other higher voltage input as well. Just don’t expect it to pump out a lot of volume.
 
Output impedance is a bit tricky to measure on HA-2 as it seems to automatically mute the headphone-out when there is no load (*which is needed for the procedure). But judging simply from the tiny voltage drop of two different resistance load, it is obvious the output impedance must be very small and indirectly confirm the OPPO number of 0.5ohm.
 

 
Subjectively, HA-2 also sounds great. The line-out has the characteristic high level of transparency that the ESS Sabre DAC is famous for, but without being too dry or ‘digital sounding’. The headphone amp section itself is also very transparent and neutral. As a standalone amp, HA-2 is very comparable to my FiiO E12DIY, which has been specifically tuned for maximum transparency. I’ll say E12DIY might have better rendering of 3D space, but HA-2 does have an airier presentation. Beyond those, I’ll say HA-2 stands shoulder to shoulder with E12DIY as one of the best sounding portable amps I have heard, regardless of price. One option to spice thing up just a little bit is the bass boost - which really is more of a mild sub-bass boost rather than a full-on rock-your-socks-off bass boost. It gives a bit more substance to the lower range but I doubt it will be enough for any hardcore bass lover.
 
Needless to say, the transparency of the amp section goes quite well with the transparency of the ESS Sabre DAC. Together they create one of the cleanest sounding portable amp+DAC I have ever heard. While I still prefer iFi Audio micro iDSD as a whole when it comes to amp+DAC because of the extra tuning feature on micro iDSD as well as the more musical Burr-Brown DAC’s sound, I think HA-2 does come very close as the 2^nd best. In some ways, especially if you are just looking for a clean sound, HA-2 might even be considered better. Same can be said if you are looking for a smaller devices or with wider / simpler smartphone compatibility. Even as a pure portable amp, HA-2 might have an edge over the slightly drier micro iDSD’s amp section. Metaphorically speaking, micro iDSD is more like a big cannon that can level everything you want while HA-2 is more like a sniper rifle that is better on a specific target. One thing they are equally good is their huge value for money factor, where the choice is really down to how you like to use your rig – as more of a generalist or a specialist.
 

iPod nano 5G feeding HA-2
 

iPod nano 7G feeding HA-2
 
Extra
Here are some extra notes that don’t fit in elsewhere:
 
DSD playback is pretty good on the HA-2, but with a small limitation that it can only do DSD256 in ‘native mode’, which means it is Windows and ASIO driver only and you can’t playback DSD256 on Android, even with app such as USB Audio Player Pro or Onkyo HF Player. In contrast, micro iDSD has no such issue. While I am not actually much of a DSD listener, I think it will still be great if there is a way to solve this.
 
OTG compatibility is really one of HA-2’s greatest feature. Besides being able to be used as a pure portable amp as well as an amp/DAC for PC (*requires software driver), HA-2 can also be used with most Apple devices with its MFi certification and many Android smartphone that supports USB OTG. On the iDevices’s side of things, I have not only paired HA-2 with iPod nano 7G successfully, but also the much older iPod nano 5G, which is not on the official HA-2’s support list. It is not hard to imagine how HA-2 can breathe some new life into older iPod and really transform them to audiophile grade player. On the Android’s side of things is, as usual, a bit hit or miss depends on whether your particular smartphone model will work for HA-2 or not. Based on my own experience, I know Sony Xperia Z series is probably one of the best bet for getting the best sound quality over an amp/DAC because Sony has implemented really good USB DAC driver in their version of Android and they support 24/192 by default. Even without a native USB DAC driver, apps such as USB Audio Player Pro or Onkyo HF Player might still work, though you’ll have to try them out personally to find out. Last but not least is the surprise OTG compatibility of Sony A10 series digital Walkman with HA-2, though the right cable is needed in order for them to work together. That however can be buy from Taobao or Amazon. With A10 as the digital source and HA-2 as the amp+DAC, the A10 really goes from just a decent sounding DAP to one of the best portable ‘audio stack’ around. This setup will really worthwhile if you are like me - which usually doesn’t like to use smartphone as digital source, but doesn’t mind carrying around a ‘stack’. Plus, the stack isn't that big anyway.
 
Those of you who prefer to build your own HA-2 cable for Sony A10 can find a DIY guide here.
 
Sum-up
I remember that the first MFi certified DAC for iPod I have ever read about had a price tag higher than the iPod itself, and it didn’t even have an amp section. Now we have the HA-2 - MFi certified with a quality amp section and Android smartphone compatible, priced only at US$299. While time does usually lower the price of tech, HA-2 still presents some incredible value - especially since most of the competition are still much higher priced. It is a gem, and no two way about it.
 
A thanks for OPPO Digital for the review loaner.

Signature Acoustics is a brand created by the India based audio retailer Pristine Note. Their first offering is the Elements C-12 - an IEM that took them 18 months of R&D, completed with a full wooden housing and aims to deliver the best bang for the bucks with an estimated price of US$50~60 with international release.
 

 
Spec
Driver: 8 mm (CCAW) Dynamic
Impedance: 18 Ohms @ 1Khz
Frequency: 17 Hz to 20 Khz         
Sensitivity: 102 dB
Cable length: 1.2m (split length 28 cms)
Channel Imbalance: Less than 2.5% dB @ 1 Khz
 

 
Packaging, Accessories and Build Quality
The C-12 comes on a fairly innocent looking black paper box - nothing too fancy or eye catching at first look. Inside, you will find the IEM, 4 pairs of eartips (S, 2xM, L), a shirt clip, two set of filters, either leather or brass case, depends of what package you are paying. The leather case, which looks and smells like real leather (and probably is), will come standard with C-12. The brass case package will cost a few dollars more. Practicality wise, the leather case is probably the better choice. But the brass case does look very impressive in person and probably great as a jewelry case. Considered that the IEM itself has a fairly inexpensive price tag, both cases are rather outstanding addition that elevates the whole package. The extra filters are also another great addon. One set is the same as those installed on the nozzle, while the other is a denser variance (with higher acoustic impedance) to tune for a slightly different sound.
 
Build quality is above average. The whole wooden housing doesn’t look quite as good a finish as Crossroads’ Woody or ThinkSound’s models and probably be better with a darker lacquer, but it is still solid. The cable looks and feels quite durable with a similar twisted wires finishing like the early Branwavz M2, but with some minor memory effect. All and all, it isn’t the best I have seen in the price range but far from the worst either.
 

 
Sound Quality
The IEM has been given 50 hours of burn-in before the review.
 
C-12 sounds warm and smooth, with emphasis on lush and richness. Bass reaches down deep, but rolls off in lower sub-bass so it doesn’t quite have the deep rumbling sensation. It is however quite abundance in quantity from mid to upper bass, not particularly boomy though definitely presents at most time, and can almost be classified as bass dominance. Lower mid is lush and rich, which are the signature sound of wood housing. However, the upper mid to treble are a bit too polite, lacking sweetness, crispiness and sparkle to highlight the micro-detail and air, and in turn makes vocal, especially female, sounds smooth, if not a bit dull. It is however still slightly ahead of that of Brainwavz M2 or M3 in drawing out detail. With a few dB of treble boost however, C-12 can really shines. Despite restricted air, soundstage is still very good, and better on width than depth. It is probably benefited from the wood housing which from my own experience, always delivers a more specious, nicely resonated sound than metal. All and all, the C-12 compares well to the similarly priced (and also bass heavy) beyerdynamic XP1 as well as early Brainwavz models, which is not too shabby for any company’s first IEM. The lushness of the C-12 will most appeal to those who are looking for easy going and fatigue-free sound, especially if you don’t mind a bit of bass in the mix.
 

 
Verdict
Despite being in India, a country that is not known for having audiophile’s headphone company, Signature Acoustics is passing with flying colors with their firstborn, the Element C-12. While it isn’t the be-all-end-all by any long shot, it is a statement to show that the company does know what it is doing and able to produce an IEM that can stand shoulder to shoulder with the competition – and that’s something they can be proud of.
 
A thank to Signature Acoustics for the sample.

I have covered Tube Amp’s portable amps in the past (here and here). While the company is called ‘Tube Amp’, they don’t limit themselves to only tube amp, but also discrete amp. The LF-15 however is their first venture into the world of desktop gears with another fully discrete design, priced around US$450.
 

 
Spec
Frequency response:20Hz~30kHz
Maximum Output：82mW (+20dBm) 1kHz 600Ω or 633mW (+20dBm) 1kHz 40Ω
Input: XLR or RCA
Total Harmonic Distortion: Less than 0.06% (1kHz)
Signal to Noise Ratio: -91dB
Recommended Headphone Impedance: 32Ω~600Ω
Power Supply Voltage: 110/220V 60/50HZ
Fuse (slow-blow fuse): 250V/50Hz,1A
Power Consumption: 15W
Dimension: (W x D x H) 23.5 mm x 288mm x x80mm
Net Weight: 2.4kg
 

 
Build Quality
The overall build quality is pretty solid. Really nothing fancy to talk about, nor is it any particular weak spot to complain for. If anything, the housing is a bit bland with just a black metal box and two big knobs. The PCB inside seems to be well arranged and again, nothing really to praise or complain about. While the components are probably hand soldered, the PCB itself doesn’t look DIY’ish, which is of course a good thing.
 
The amp can operate on both 110V and 220V AC, so it should be fine to use in just about everywhere that has a power socket. It takes both RCA and XLR input, though only has a single ended 6.35mm stereo output.
 
Gain and Hiss
I have complained in the past that Tube Amp’s portable amps all having too high a gain and unfortunately I have to make the same complaint again. By measurement, the LF-15 has a fixed gain of about +19dB, which is just way too much for the majority of headphone out there. The high gain also makes LF-15 hissy. While I can’t hear any hiss when music is playing, it is definitely quite noticeable in silence passage. The only workaround is to use higher impedance, less sensitive headphone. But a real cure would have been a gain switch that allows better matching of gain and headphone.
 
Sound Quality
As always, I started my evaluation of LF-15 with a RMAA measurement. For the most parts, it doesn’t quite able to compete with my reference O2 but still good enough that I don’t see a problem – however, there are two areas that don’t perform well: Intermodulation Distortion and Stereo Crosstalk. That is strange as I can’t say I have heard anything out of place as the measurement would have indicated, then I realised it might have been a side effect caused by the permanent bass boost that built into LF-15 rather than any actual bad performance. If you look at the FR curve below, you will see that there is a very big sub-bass boost, regardless of whether the ‘tone’ knob is all the way to the left (*TL curve in graph) or to the right (*TR curve in graph). RMAA probably just mistook these bass boost as some kind of distortion when running its test (as those tests involve low frequencies). One area that does indeed not doing so well is its current output – while LF-15 has way too much voltage gain, its current output is really on the weak side. Last but not least, the output impedance is also pretty high, measured and calculated at around 16 ohm.
 

 
Subjective listening wise, LF-15 is actually quite good. The presentation is neither too tube’ish and musical, nor is it clean and neutral. It is more or less in the middle ground, and perhaps just a bit over to the musical size. Though I won’t say it is in any obvious way euphonic sounding, it does have somewhat of a smooth sound. Due to the sub-bass boost, bass kick and extension are quite excellent – but can be a double edge sword if you already have a really bass heavy headphone or simply doesn’t like that much bass. Though the good news is that the boost is all in the sub-bass region and doesn’t intrude the mid-range at all. An even better news would have been a user selectable bass boost switch, which would have made the LF-15 a more versatile amp. One setting that user does get to play with is the ‘tone’ knob, which doesn’t seem to vary the frequency response that much but there are fairly audible change in the presentation. With the tone all the way to the left, the presentation is on a warmer and smoother side; with the tone all the way to the right, the presentation changes toward a cleaner and detail oriented sound. It is almost like the tone knob is changing the focus of the presentation between the mid-low and upper mid-high range, though I can’t be sure of the exact mechanism behind it. Last but not least, the soundstage is quite good. Not the best of width or depth I have ever heard, but definitely above average and fairly immersive while not restricting.
 

 
Sum-up
All and all, my feeling is a bit mixed regarding LF-15. While it sounds good, the permanent bass boost, high gain and low current output, plus the high output impedance limits its usage more or less toward higher impedance, single driver full size headphones, and that inherently restricts its appeal to a wider audience. I like Tube Amp’s products because I know they always aim to deliver unique and original implementation for their amp instead of following the trend, but sometime it is that uniqueness that hinders the its practicality. I really like to see Tube Amp next product has more user selectable settings - but for now, I’ll say that LF-15 is not for everyone.
 
A thanks to Tube Amp for the review sample.

It has been 3 years since my original review of iFi Audio’s original micro iUSB Power, iDAC and iCAN. Fantastic when they are first released and, in my opinion, still quite relevant after all these time (*with the testimony that they still form part of my PC audio chain), the competition has however certainly stiffen up a bit. In respond to the fast pace of the current digital audio gears market, iFi Audio has decided to update the original models with newer parts, better tech, still excellent sound quality and always a big bang for the buck. The nano iUSB3.0, micro iDAC2 and iCAN SE are priced $199, $349 and $390.
 

(nano iUSB3.0 package not show)
 
Spec

(Accessories not fully show)
 
Nano iUSB3.0
Output Voltage: 5V±0.5%
Output Current: 2.1A
Noise floor: 0.5uV (0.0000005V)
USB 3.0: Ultra-speed 5.0Gbps
Input Voltage: AC 100 – 240V, 50/60Hz (iFi iPower included)
Power consumption: Less than 15W (includes powered USB device)
Dimensions: 87(l) x 68(w) x 28(h) mm
Weight: 141g (0.31 lbs)
 

 
Micro iDAC2
Input: USB3.0 (USB2.0 compatible)
Output:
    SPDIF RCA (only PCM up to 192KHz)
   Audio RCA
   3.5mm Headphone
Formats:
    44.1/48/88.2/96/176.4/192/384KHz PCM
    2.8/3.1/5.6/6.2/11.2/12.4MHz DSD
    353/384KHz DXD
 
DAC: Bit-Perfect DSD & DXD DAC by Burr Brown (1-DAC Chip; 2-Channel; 4 Signals)
 
Filters:
-PCM: Bit-Perfect/Minimum Phase/Standard, Digital filters selectable
-DSD: Extreme/Extended/Standard, Analogue filters selectable
-DXD: Bit-Perfect Processing, Fixed Analogue filter
 
Line Section:
Output: 2.1V (+/-0.05V) fixed
Zout: Under 39 Ohm
SNR: Over 114dB (A) @ 0dBFS
THD+N:
    Under 0.0025% @ 0dBFS (100k Load)
    Under 0.025% @ 0dBFS (600R Load)
 
Headphone Section:    
Output:
    Over 350mW (2.40V) into 16R (<10% THD+N)
    Over 34mW (3.20V) into 300R (< 0.1% THD+N)
Zout: Under 2 Ohm
THD+N: Under 0.0025% (1V into 16 Ohm, 0dBFS)
SNR: Over 114dBA (3.2V into 16 Ohm, 0dBFS)
Power consumption: Less than 1.5W
Dimensions: 158(l) x 68(w) x 28(h) mm
Weight: 265g (0.58 lbs)
 

 
Micro iCAN SE
EQ: Two levels selectable 3D Holographic Sound and XBass
Gain: 0dB, 12dB and 24dB user-selectable. Full discrete, Class A
Buffer Stage: TPA6120A2
SNR: Over 123dB (A)
THD: Under 0.003% (400mV/150R)
Frequency Response: 0.5Hz to 500KHz (-3dB)
Output Impedance: Under 1 ohm
Output Power: Over 4000mW (16Ω)
Output Voltage: Over 10V (over 600Ω)
Input Voltage: AC 100 – 240V, 50/60Hz
Power Consumption: Under 5W idle, 12W max.
Dimensions: 158(l) x 68(w) x 28(h) mm
Weight: 216g (0.48 lbs)
 
Accessories and Build Quality
Design, accessories and build quality wise, the new offerings are pretty much top notch and on par with their older sibling. I have said in the past that I am not that biggest fans for iFi long and narrow Micro casing, but that has become part of iFi identity. With micro iDAC2, you will get some rubber feet, a short USB cable and RCA cable. Micro iCAN SE, there are the power adapter, short RCA cable, 6.4mm-to-3.5mm stereo adapter, a flat head screw driver for adjusting gain, 3.5mm interconnecting cable and rubber feet. With nano iUSB3.0, there are USB3.0 cable, rubber feet and power adapter. One thing to note is that the power adapter of all of current iFi has been upgraded to the iPower adapter, which offer even cleaner power than the original ULN adapter. To nit-pick, I am not too fond of the new customized 3M rubber feet that is lower than the original 3M feet, making it harder to stack the iDAC3 and iCAN SE on top of each other as the metal casing are touching each other. At the end, I end up getting some taller original 3M rubber feet so I can stack them up for a cleaner looking. Of course, whether this will bother you or not totally depends on how you like to arrange your iFi gears.
 
Gain and Hiss
Line-out on iDAC2 is the fairly standard 1.98Vrms, headphone-out gain is just over 5dB, or about 3.6Vrms at max. Gain on iCAN SE is however selectable at either 0dB, 12dB or 24dB. Assuming iDAC2 as source, most headphone and IEM will be more than enough with 0dB gain. Hard-to-drive full sized might benefit from the 12dB gain, where 24dB gain with just over 11Vrms output is probably reserved for really low sensitive headphones.
 
Hiss is very well behaved on the IDAC2. With the hiss-prone Shure SE530, I didn’t notice any hiss until around 2~3 o’clock on the volume knob – which is of course impossible to actually listen on such a high volume during music playback. I think it is safe to say there is little to no chance you will notice any hiss with sensitive IEM on normal use.
 
Hiss on iCAN SE is mostly positive. I say ‘mostly’ because as far as hiss goes, it is on par with the original iCAN where low level hiss is only noticeable with volume knob going pass 12 o’clock. But I also noticed the 15V iPower seems to be more sensitive to voltage irregularity and ground loop from the main, which could give a very faint switching noise in rare occasions. If I switched to using the 9V iPower to power the iCAN SE, the faint switching noise will go away. Not really sure if that’s due to the particular 15V iPower adapter I have as I don’t have another 15V iPower adapter to compare it to, plus I can’t replicate the situation easily. Will probably have to wait till I get another 15V iPower to double check though I think it is more likely a freak incident.
 
Sound Quality
As usual, we start with the look at some basic measurement. As far as RMAA goes, both iDAC2 and iCAN SE pass with flying color with flat frequency response end-to-end, and great looking numbers on crosstalk, SNR and IMD. Then again, these result are to be expected, given the original IDAC and iCAN already measure quite well. Output impedance on iDAC2 headphone-out is measured and calculated to about 1.9ohm, in line with the listed spec, and it has plenty of output power to my dummy load. iCAN SE fairs even better with just 0.9ohm output impedance and higher output power. All and all, the technical side of both iDAC2 and iCAN SE seem very solid.
 

 

 
Let begin with iDAC2. Besides sharing the same name with the original iDAC, there is really nothing really similar between the two. Where the original iDAC is meant to be a step beyond entry level USB DAC, the iDAC2 simply takes it to the next level. Instead of the entry level ESS chip, the iDAC2 uses the same DAC chip as better sounding iDSD series. I think it is fair to say iDAC2 is really more of a desktop version the iDSD series, where performance is in between the nano iDSD and Micro iDSD. On the DAC section, it shares many of the same features as nano iDSD like native DSD playback and filter selection (see my micro iDSD review for more detail on these features). On the analog section, it is a noticeable improvement over nano iDSD but not as robust as the flagship micro iDSD. One of the minor complaint I have with nano iDSD is that its headphone amp section is kind of the weakest link. But that is not the case on iDAC2. The bigger size and no need of portability means a better implemented analog section after than DAC stage, which no longer give me the feeling that there is a noticeable weak spot in the chain. While it is still not the best sounding amp section you will find on a DAC/amp, it is at least not a let-down in anyway and should drive most headphone quite well. I would think the word ‘content’ is what coming to my mind when using iDAC2 as a standalone unit – that I can be quite happy to use it as it is and there isn’t the need to ‘fix’ it in some way to make it better. Where with the original iDAC, I am more incline to use it with the iCAN because I know on the back of my head that I want just a bit more.
 

micro iDAC's FR curve
 
So how is the subjective difference between iDAC2 and iDAC? Gone is the clean, slightly sterile sound of the ESS chip and in is the more musical presentation of the Burr Brown DAC that I am quite fond of. Same can be said on the headphone amp section as well. While it is still reference flat on FR curve, the overall tonal is richer and more musical than the colder sounding iDAC’s headphone-out. The dual-mono like implementation of two MAX97220 headphone driver gives plenty of power and control. The lower in overall gain makes it a bit more IEM friendly than the iDAC. It doesn’t have the output to handle really hard-to-drive headphone but that is what iCAN SE is for. All and all, the iDAC2 is a solid upgrade over the original model. I’ll dare to even say it is almost a quantum leap in design.
 

 

 
Different from the radical change between iDAC and iDAC2, there are more similarities between iCAN SE and iCAN. Their basic topology shares the same DNA with TubeState Class A discrete gain stage followed by TPA6120A2 headphone buffer stage. Of course, the excellent 3D Holographic Sound (3DHS) and XBass are there as well. The main difference is that the iCAN SE, with a higher voltage supply from the 15V iPower adapter, can pump out 10 times the power (4W vs. 0.4W) over the same 16ohm load when compared to the original iCAN as well as having a higher maximum gain for the most demanding of headphone.
 

micro iCAN SE's FR curve
 
So does the iCAN SE sounds the same as the already great iCAN? Well, yes and no. It is easy to tell that iCAN SE inheres the same underlying tonality and transparent presentation from iCAN, but there are a few subtle improvement. First, the overall image is about 10% larger on the iCAN SE, which isn’t much but enough to paint out a larger sonic picture and result in a slight improvement over positioning. Secondly, the extra power really helps to tighten up the presentation with crispier top notes and harder hitting low notes, which gives better definition. These improvements are not night and day by any mean, but enough to be noticeable in a volume matched comparison. I guess it is rather befitting that iFi has managed to make the iCAN SE even more ‘special’ than the original iCAN.
 

micro iCAN SE's XBass
 
Lastly, the implementation on iCAN SE’s 3DHS and XBass seem to be identical to that of the original iCAN. 3DHS can’t be easily measured using my equipment but I did measure the XBass EQ and they are indeed the same as the original iCAN. 3DHS, on my ears, also sounds extremely similar (if not identical) too. Like they said - if it didn’t break, don’t fix it. I am glad to see iFi has kept the excellent 3DHS and XBass intact.
 

 

 
I have said on my original iUSB Power’s review that I didn’t actually get it for the use with the original iDAC, though the end result does show improvement for the pairing. Compare to the iUSB Power for only cleaning up the USB power line, the new nano iUSB3.0 is also a fully suited up USB3.0 hub that not only clean up power line, but also clean up the USB data signal as well as supporting BC1.2 profile. It is pretty much as audiophile as USB hub can ever be. Of course, whether you will detect an improvement with or without nano iUSB3.0 depends on how good or bad your PC’s USB connection is. If it doesn’t have much problem to begin with, then you might not notice much improvement. If it does have problem, then the nano iUSB3.0 will prove to be a good fix. My main use of the nano iUSB3.0 is to connect my micro iDSD to the PC so the iDSD can get a clean BC1.2 power supply line and won’t drain its internal battery over time - and It does a fine job there. Like the original iUSB Power, the nano iUSB3.0 is at best a minor optimization to your rig after you have improved on other aspects. It will worth it if you already own a mid to higher end USB DAC, but probably not the best idea to pair it with a cheap USB DAC and expect it to do miracle.
 

From left: micro iDAC2, nano iUSB3.0, and micro iCAN SE
 
Summery
Since my review for iDAC, iCAN and iUSB Power some 3 years ago, the market for desktop audiophiles gear has blossomed and then somewhat shifted more toward smartphone oriented OTG products. It is rather a delight to see iFi Audio has continued to refine its nano and micro products line-up and push the envelope of offering audio gear with exceptionally good price-performance ratio, not just a mad dash to keep releasing the latest and greatest purely to meet the bottom line.
 
A thanks to iFi Audio for the iDAC2 and iCAN SE sample.

ASUS ventures into the sound card business in 2008 and released their first audiophiles targeted Xonar Essence series in mid-2009. The STU is the latest addition to the line-up. According to ASUS’s press release, the STU is intent to be an USB version of the PCI-e based ST/STX models, with extra features no less. Price wise, the US$399 price tag places it right in the middle of the Essence family, doubling from ST/STX, but half of the flagship One MUSES edition. But the real question, how does it stand on itself?
 

 
Spec
SNR (A-Weighted):
Line Out: 120dB
Headphone: 117dB
THD+N at 1kHz:
Line Out: 0.00036 % @ -108dB
Headphone: -101dB
Frequency Response (-3dB, 24bit/192KHz input): 10 Hz to 48 KHz
Output/Input Full-Scale Voltage:
Unbalanced Output: 2 Vrms
Headphone: 7 Vrms
Bus Compatibility: USB 2.0 high-speed
Chipset
Audio Processor: C-Media CM6631A
S/PDIF: TI PCM9211
DAC: TI PCM1792A
I/V: LME49720 x 2 (Swappable)
LPF: LM4562 (Swappable)
Headphone Opamp: TI TPA6120A2
DC Servo: TI OPA2132 (Swappable)
Sample Rate and Resolution
Analog Playback Sample Rate and Resolution:
44.1K/48K/88.2K/96K/176.4K/192KHz @ 16bit/24bit
ASIO Driver Support:
44.1K/48K/88.2K/96K/176.4K/192KHz @ 16bit/24bit
Output impedance:
Line out: 100 ohm
Headphone out: 10 ohm
Clock:
Crystal clock: 12MHz
Oscillator: 45.1584MHz (44.1kHz); 49.152MHz (48kHz)
Connectivity
Analog Output
1 x 6.3 mm jack (1/4") Headphone out
2 x RCA (Un-Balanced)
Digital
2 x S/PDIF in (1 x Optical / 1 x Coaxial)
1 x Aux in 3.5mm jack (1/8”)
1 x USB 2.0
 

 
Accessories and Build Quality
My review unit of STU is an early sample. Though it should be the same as the retail unit, it didn’t come in a retail packaging so I am not sure whether there are other accessories being included or not (though the question is, does it need any extra accessories?) . Basically, the unit comes with an AC wall adapter as well as a vertical stand, a 6.35mm to 3.5mm stereo adapter and USB cable of course. The AC wall adapter looks like a miniaturized notebook adapter and it pumps out 12V, 3A of power. While STU is designed to seat flat on the desktop with its 4 non-removable feet, it actually doesn’t look half bad standing vertically either. The stand has rubber strips that clip onto the body using friction and hold it up firmly. The unit is heavy enough (with stand, 780g) that it is not going to move around much.
 
The build quality is excellent overall – not surprising given ASUS already has a good reputation as a PC maker. On the back there are the gain switch for headphone-out, RCA line-out, AUX-in to use STU purely as an amp, both optical (Toslink) and Coaxial S/PDIF inputs as well as the USB input. On the front, there are the power switch and the input switch that lets you choose between USB, coax, optical and aux inputs. There are also two volume knobs – one for headphone-out while the other is for the RCA-out on the back, just in case if you want to use STU as a preamp. Last but not least, there is the ¼’ headphone-out. The front panel also has a row of white LED to indicate which input you are using, the gain setting as well as a ‘bit perfect’ mode. The ‘bit perfect’ LED will only lights up when you are using the STU’s ASIO driver on the PC.
 

 

 
Gain, Hiss, Pop and Channel Balance
Though the RCA-out does output full 2Vrms line signal, it is controllable via the front ‘preamp’ volume knob. It is a useful feature if you are using STU as a preamp to feed a power amp. But for those who rather want a fixed 2Vrms output, you can set the bypass jump inside (which is accessible once you open the top panel) to bypass the volume knob all together. I have done some RMAA measurement over the line-out on both maxed-out and bypassed mode, and the result comes back identical. If you didn’t bother to set the bypass jumper, maxing the preamp knob should be almost just as good. The headphone-out has two gain settings. The low gain is about -2.8dB while the high gain is about 10.5dB. Unlike your typical gain switch which instantly changes the gain with a flip, ASUS implemented the gain switch in a rather considerate manner. To avoid accidental gain change, you must unplug the stereo jack first. Then and only then the unit will allow you to change the gain.
 
Hiss is pretty much a non-issue in low gain as it remains dead silence even when maxed out. It does begin to hiss very faintly when the volume knob passes 12 o’clock in high gain, but any headphone that needs so much volume is unlikely to be sensitive enough to pick up the hiss anyway. I did notice the unit ‘hums’ a little when it is not connected to USB (i.e. when using the S/PDIF input from a portable source). It seems to be a symptom of improper grounding as it disappears as soon as when it is connected to USB or when the casing is grounded (*touched by hand). This shouldn’t be a problem as long as the STU is used mainly as an USB DAC with the occasionally S/PDIF input (which means it will be connected to USB all the time). But it might be something to consider if you are planning to use it as a standalone unit.
 
With the default setup, the STU doesn’t have much of any click and pop issue during startup. ASUS does however implemented an OPA2132 based DC servo to deal with any possible pop or DC offset issue. RMAA measurement shows that the DC servo circuit doesn’t really affect the performance so my suggestion is to leave it on. You can bypass it if you like. However, I do strongly advise you keep the DC servo on if you have rolled the opamp on I/V or LPF stage (*more on opamp rolling at later discussion). This is especially important if you have used MUSES01 as it does create a rather big pop during startup.
 
If you pop open the casing, you can find two variable resistors next to the TPA6120A2 chip (light blue ‘blocks’ with screw on top, one on the right and the other on the left of the chip). In case of channel imbalance, you can turn the screw on of them until the channel is balanced. So how do you know the channels are balanced? The best way is to play a fixed tone (i.e. 1kHz) and use a multimeter to measure the AC voltage of headphone-out. If both channels matched, then the channels are balanced. Supposedly the unit should be well balanced when you received it, but it is also good to know there is something you can do if it is not.
 

Size Comparison (left): iFi Audio iDAC, STU and Leckerton Audio UHA-4
 
Sound Quality
On spec, STU really looks good. I have no reason to doubt ASUS’s number. But just in case, I did some RMAA measurement of my own and the result is pretty positive for both line-out and headphone-out: mainly flat FR curve and low noise. Power wise, the TPA6120A2 on the STU’s headphone-out behaves similarly to FiiO E9 / E09K and FireStone Audio Fireye HD (all three use the same TPA6120A2 chip) – good in voltage but only okay on current, especially into low impedance load. This is probably because of the high output impedance of 10 ohm required by TPA6120A2, which can be a downer if you mainly use low impedance multi-drivers IEM and coloration is an issue. It would have been better if ASUS was able to lower the output impedance by bypassing the output resistors with inductors. iFi Audio has used the same trick on iCAN with good result.
 
Subjectively, STU’s amp section is very similar to that of FiiO E9/E09K. The only difference is that FiiO has a fraction better bass slam which gives it a better impression on dynamic. Beyond that, I’ll say they are within 95% of each other. Still, STU amp section doesn’t quite compete with iFi Audio iCAN that employs the same chip. iCAN just sounds more authority, tighter, better textured and grander in overall presentation. It is not to say STU’s amp section sounds bad – just not the best of what I have heard of TPA6120A2.
 
Now to the DAC section of STU – it will take USB or S/PDIF input with just about every bitdepth and bitrate commonly used. Also, it supports asynchronous USB mode as well as a build-in ASIO driver for those of you who crave for some bit-perfect moment. The DAC chip itself is the current TI’s flagship PCM1792. The sound of PCM1792 reminds me a lot about the (TI’s previous flagship) PCM1704 in HifiMan HM801 – silky smooth, warm, full and well textured. It is a musical and relaxing sound that leans toward an euphonic presentation and very much on the opposite of ESS Sabre’s aggressive and dynamic sound that tends to highlight micro-detail and transparency. Perhaps not the best way to describe them, but I thought they represent a good case of what analog vs. digital sound is about. Technically, I won’t say PCM1792 in STU sounds any lesser compared to any EES Sabre’s chips (including the basic ES9023 in ODAC to the higher end ES9018 in HifiMan HM901), but going back and forth for comparison always leaves me the impression that, while ESS wants you to hear each music note as clean as possible, the TI chip wants to envelop and submerge you inside the music. That’s how I feel every time I switched from one to the other. But do take note that I am not talking about any major day and night difference – it is really the subtleness of sonic character between them that gives the different feelings. Ignoring the comparison, STU still sounds very transparent and neutral on its own.
 
Last but not least – the sound of the DAC section can be ‘tuned’ by rolling in different opamps. That’s what next in the discussion:
 

 

 
Opamp Rolling
One of the big selling points of the Essence series is that it allows the user to roll in different opamps combo to fine tune the sound. In the STU, there are 4 opamp you can swap out, including the dual opamp on the I/V stage (converting the current output of the DAC chip to voltage), one on the LPF stage (Low Pass Filter, for cutting out unwanted high frequency over 20kHz) as well as one for the DC servo (for eliminating DC offset / pop during startup).  In theory, the DC servo circuit should have minimum effect to the final sound so I didn’t bother to swap its opamp. I did listen to the headphone-out with the DC servo enable / disable and didn’t notice any obvious sound quality difference. So I focused only on the I/V and LPF stage. With I/V opamp rolling, I kept using the stock LM4562 for LPF. With LPF opamp rolling, I used the stock LM49720 for I/V instead. One important thing to note is that the opamp voltage supply is about +/-12V, so you must be sure the opamp you swap in is at least rated for that voltage.
 
I/V opamp rolling (LPF: LM4562)
LM49720 Stock– well balanced, clean, airy and open but slightly to the warm side.
LM49720 ‘Metal Can’– almost identical to stock, but just a tap fuller in body.
OPA2604 – denser, not as airy and open as stock.
OPA2209 – bass note is a little lean, good height.
OP270 – Also dense, but a little better soundstage than OPA2604.
OP275 – Leaner and brighter than stock, almost grainy. Good soundstage.
AD8066 – Even brighter than OP275, but without the graininess. Slightly flat in soundstage but good width.
OPA2227 – Forward, full and bright, slightly grainy.
OPA2134 – More mid centric, lack soundstage.
MUSES01 – Similar to Stock, with better dynamic and impressive soundstage.
MUSES920 – full and forward, like smoother OPA2227.
 
LPF opamp rolling (I/V: LM49720)
LM4562 – stock, again: well balanced, clean, airy and open but slightly to the warm side.
LM49720 ‘Metal Can’ – Similar to stock, slightly less dense and more open in the mid.
OPA2604 – thick and slow, grainy.
OPA2209 – Full, similar to OPA2604 but without being overly thick and slow.
OP270 – Lean, slightly lacking in bass, slightly bright.
OP275 – Well balanced, though soundstage isn’t great.
AD8066 – Very airy and open, great soundstage but a little bright.
AD8620 – Like a tuned down version of AD8066, with better body and smoother presentation.
OPA2227 – warm and slightly dull, but sparkly on the top.
OPA2134 – similar to OPA2227, more mid centric and not as sparkly.
MUSES01 – Similar to stock, but slightly better dynamic and soundstage.
MUSES8920 – somewhere between OPA2227 and OPA2134.
 
Short notes:

• I happen to have TO8 packaged LM49720 with DIP8 adapter, commonly referred as the ‘metal can’ version of the opamp. They are also usually regarded to be better sounding their DIP8/SO8 counterparts - in the case of LM49720, I’ll agree. But it isn’t really a night and day difference and not something I will lose any sleep over.
• LM4562 and LM49720 have been long rumored to be the same chip with different name. Overall, they are indeed very similar in presentation. But LM49720 tends to sound more open and relaxing without losing any detail. I’ll call that a (small) win.
• The stock combo is easily one of the best combos beside triple MUSES01. I don’t really see a strong need for upgrade given how capable the stock combo is. If you are on a small budget, I’ll suggest LM49720 for the LM4562 in LPF. AD8066 is also an interesting LPF choice as it gives unrivalled soundstage, but at the cost of texture and body. For a slightly bigger budget, perhaps MUSES01.
• LPF rolling tends to have more impact than I/V rolling.
• Though also come from the same MUSES family, MUSES8920 is nowhere as good sounding as MUSES01 in STU.
• Triple MUSES01 is by far the best sounding combo. It bests the stock combo with better dynamic and speed, plus a more opened and natural soundstage that is very well layered. But given MUSES01 is hard to find and very expensive (US$50 a pop, and you need three), I am not sure it will be the smartest investment to convert the $400 STU into a $550 unit. Still, it is unbeatable in sound.
• RMAA measurements have been carried out on quite a few of the combo. Not surprisingly they measured more or less identical. It is very likely the resolution of RMAA is just not good enough to tell the difference between these opamp combos.

 

FiiO X3 coax-out to STU sounds rather excellent.
 
Sum Up
Overall, STU is a solid unit. Features wise, it is a compact all-in-one unit that can do them all – S/PDIF, USB, and analog, no problem there. As far as sound quality goes, it is a better DAC than it is a headphone amp. Roll in some MUSES01 and pair it with a better desktop amp, and we could very well have a top-end setup there - though that could very well be just as expensive as STU’ big brother, the Essence One MUSES edition.  For a purely PC-as-source situation, I know I will likely reach out to the iFi Audio iDAC + iCAN combo, but they won’t do S/PDIF and will cost more together. The similarly priced FireStone Audio Fubar HD is also a jack-of-all-trade, but USB is limited to 24/96 while not as refined sounding overall. The only upside is that Fubar HD can be found for half price, so it is not a total lost especially for those with tight budget and willing to settle for slightly less. At the end, for being a mid-range model designed with versatility in mind, I think ASUS has done a pretty good job. The best part is, not only STU is an audio multi-tool, but there is enough room left for upgrade that will give future value to the user - that’s very much the X factor for STU and gives it a slight edge over the competition.
 
A thanks to ASUS for the review sample.