Reviews by antdroid


Headphoneus Supremus
Fun Bass IEM with good tuning
Pros: Great bass quantity, focused in subbass
Good balanced mids
Great fit
Cons: Has a slight peak in upper mids that can be bright at times
Average technical performance for its price
I've always deep down in my heart wanted to enjoy a big bassy headphone or IEM. The problem is, most of them are not very good. They are muddy, boomy, and very poor in resolution, and to balance it out, they make highs very bright, or even worse -- have no treble at all (i.e. L-shape). While there are some fun bassy sets like the Empire Ears Valkyrie and Legend X sets, they are quite pricey, and also can be a tad harsh in the highs.

Along comes Fat Freq. This is a Singaporean small boutique brand that makes a series of IEMs with big bass boosts, but with balanced mids and treble. I was enamored with the frequency response graphs I had seen from various measurement sites when I first heard about their Maestro series. They had huge bass boosts, but the mids/treble range fit right along what I like.

So, I dialed up Precogvision, and asked him to send me Fat Freq 'scheapest universal set, the Maestro Mini, since I knew he had recently reviewed it. After receiving the unit, I must say, it does exactly what I was expecting it would do. Hit bass hard.

IEM Design​

Since this was a loaner, as well as a pre-release unit, I did not have all the retail packaging and can't provide any details here. In addition, the nozzle of these units do not have a filter on them, and the driver and inner cavity of the Maestro Mini is exposed. Removing the filter may cause some sound changes.

The MM itself is a small-sized blue IEM with a very comfortable design that I found good and easy to wear. It features standard 2-pin connectors on both sides, and a FatFreq logo on the faces.

Sound Impressions​

After listening to a bunch of neutral monitors, or slightly bright gear with light or even bass boost, and then putting on the Maestro Mini, I was immediately engulfed in deep, rich and thick bass. It was startling at first. I knew I was expecting a big gain here, but it was surprising how much it was in some songs, yet how it did not come off as muddy or bloated. It was bass quantity done right.

That's because the FatFreq brand decided to bump a downsloping HUGE bass bump starting at subbass regions, making it act like a subwoofer, and not a mid-bass woofer, which can add a lot of kick and punch, but also bleed into the midrange. With this amount of bass increase, 20 decibels above the midrange, you really need to be careful how this tuning can affect the overall tonality.

The Maestro Mini, for the most part, does this quite well. So, normally I talk about the general sound, but it's taking me three paragraphs to get to the point. This is a big bass in-ear monitor that has surprisingly well balanced mids and smooth treble. There are sometimes hints of a some brightness in the upper-midrange, and that could possible be attributed to the filterless design of this prototype. In production models, there is a nozzle filter, and that may tame the brightness a tad.

How does the Maestro Mini do technically? It's alright. I would say it's average. There's nothing wrong with it. There's nothing special about it either, besides its not-so-secret weapon of big sub-bass, and in this regard, it does it very well. It's not the most detailed IEM at the $450 price range, and its not blobby either. It's just good, or good enough. The bass quality is a step or two below the Empire Ears dynamic driver IEMs like the Odin and Legend X, but its quite competitive with name-your-chifi product of the month, and likely beats it when you consider that the bass driver is pushed to its limits here.

The soundstage isn't huge -- its fairly average for an IEM, which means its small, but acceptable. Imaging is just okay, and depth is alright. I wouldn't be looking at the Maestro Mini as a technical wizard, as it is not. It plays much better as a fun, fun IEM that actually sounds quite pleasant and enjoyable.

Final Words​

So, if you are a big bass lover, but also want something that can actually work across genres well, this is a pretty good IEM, and its priced decently well for a possibly niche area where there isn't a lot of stuff that excels in pure bass quality.
The newer units of the Maestro Mini have an included filter in the nozzle now, fortunately.


Headphoneus Supremus
Pros: Refined, smooth sound
Most coherent MEST yet
Great case included
Attractive looks
Warm, pleasant tuning, easy to enjoy
Cons: Cable is very nicely built, but very stiff
Not as exciting and big soundstage as prior MEST

The MEST series has been one of my favorite IEM lines since Unique Melody first came out with the original bone conductor-featuring quadbrid earphone. The original MEST had used two "new" IEM technologies at the time with a bone conducting driver and electrostatic tweeters to go along with a dynamic driver and a series of balanced armature drivers. This review will take a look at the company's newest MEST branded product, the MEST MK3.

The original MK3 prototype and design that was shown around featured a ceramic shell with a plain looking design that had some mixed opinions. After running into supply-chain issues with the ceramic material for the shells, and collecting feedback, the UM team decided to use a more familiar and popular look from their limited run Indigo product and released the MEST MK3 in a similar blue and a new red colorway. The one I was sent for review from Unique Melody is of the blue variety.

With a shiny gold rim, and translucent blue faceplate and shell that displays little pieces of carbon fiber within it, the MEST MK3 is really a nice looking IEM. It has a very comfortable medium-to-large shell size that fits me perfectly. I was able to wear this for hours at work without problems. The shell is made from a lightweight plastic, which also helps with the long-term comfort.

The custom cable that comes with the MK3 comes from PW Audio, and is designed to match the looks of the shell design. The connectors are come painted in a popping blue color and are very well-built. The Y-splitter, and chin strap are also matching in color and metal material. The cable is 2-core, but with each core shielded and thick. The lower portion of the cable is rather stiff, as it isn't woven, and instead has both of the L/R cables running in parallel with each other, and wrapped with a fabric braided sheathing in dark blue. While its a very nice looking cable, I do find the extra stiffness and weight to be a little annoying to use in practice. It is not too bad if you are stationary, but if you're moving around, the cable can be a frustrating experience.

In addition to the cable, the MEST MK3 also comes with a beautiful and well-designed leather case. This case is a round 2-piece design with a smaller lower cylinder where the products go into, and an upper, larger top that closes down on it. It's one of my most favorite included cases with an IEM that I've seen yet, and I even like it more than the very cool Dignis zipper case that came with the MEST MK2 and MK1 prior.

One of the newer products from Unique Melody that is also included with this IEM and the previously reviewed U-FREE truely wireless IEM is their umbrella-shaped tips. This pairing, however, is quite bad with the MEST MK3, and one I would not recommend -- at least in my experience. I'll discuss why in my sound impressions section, but I did end up finding great fit and sound with my typical sets of SpinFit tips that I use with most of my IEM reviews.

As with prior MEST products, their packaging contents are very good and if not top notch. I only wish they pick a more softer cable, and its the same nitpick I've had through all their products. But everything else is great, and I can't deny that the cable looks fantastic and well-built.

Sound Impressions​

MEST MK3 takes a similar approach to tuning as prior MEST IEMs. It stays on the warmer and slightly darker side of neutral, and comes across as a warm-bodied, and very pleasantly tuned in-ear. It has a slightly elevated bass range, steady mids, and a darker treble range that is well-extended on both ends of the spectrum. I find it a very solid darker U-Shape tuning, and should be very familiar to those who have listened to prior MESTs.

While general tonal balance is similar, though not exactly the same, the approach on the rest of the tuning does differ. There is definite MEST DNA in the MK3 - with a similar driver configuration, and overall design, but the MK3 refines the overall sound significantly, over both the MK2 and MK1. This is, by far, more coherent than the other two, and comes across very smooth and lacking a sense of disjointed bass that the other two presented to me -- whether that was for good and for bad.

Now that said, that lack of full cohesion, did give the original MEST its charm. It's bass felt isolated and singular, away from the rest of the mid-range and treble, and the upper-midrange had a very unique holographic sound to it, that also sounded weird, and different and made it so original-sounding at the time. The MK2 cleaned it up a bit, and maybe to its dismay, made the MEST MK2 sound a bit ordinary, albeit still very good.

The MK3 doesn't necessarily have these issues, or benefits, depending on your preferences. It still retains the holographic soundstage that all of the UM Bone Conducting products exhibit, but it brings everything together more coherently, and packaged better. It does not sound ordinary like the MK2 does, and it doesn't sound crazy like the MK1 did -- it's somewhere in between with a nice sweet spot of just sounding good.

The resolution on the MK3 is excellent. At first, I tried using the included UM tips, which are very soft and reminiscent of the Azla Xelastec tips, except these have scalloped edges that make it look like an umbrella. With these tips, the resolution is very apparent, but it also killed all depth, soundstage, and imaging from the product. I actually was shocked at how untechnical the MEST MK3 sounded at first, because the included tips were the first set I tried the MEST on. They fit great and everything, but the sound was like someone shouting into my ears.

With different tips, and literally any other tip, the sound presentation opened up and the stage widened and deepened, and it felt much more natural and more like something I was expecting for a $2000 IEM. The soundstage is still smaller and more intimate than my CIEM MEST MK1 and the universal MEST MK2 I compared the MK3 against, but it was fine, and the differences in stage were very little.

The resolution was much the same. The other MEST excelled at bringing out the micro-details from recordings, and I did not feel the MK3 gave up any of this at all. It only made them less sharp and more natural.

Yes, the MK3 is probably the most musical of the three that I have and compared against. It doesn't go for the most precision edges, nor the biggest bass bloom, but it just has a nicely tight knit and warm sound that is very easy to enjoy and get lost in the music with, and it does not suffer from the occasional blips where the upper-mids and treble can be a bit bright and harsh that the others experience. It's very sweet and gentle in its treble presentation in this regard.

Listening to different music genres with the MEST MK3 gave me some insight into which I prefer most with the MK3. This isn't a neutral IEM that is indifferent to musical choices. It's pretty close though. For my liking, I really enjoyed the MK3 out of music with brighter notes, and shriller highs. It went well with classical and jazz music, where a variety of instruments are at play, and it tames the horns and strings well, without losing the quality of the sound -- in fact making them sound sometimes more warm and natural.

In rock music, I did find the darker tonality to be beneficial for some music and perhaps suffocating some other songs. For tracks with an excessive amount of electric guitars buzzing like metal, this combination really does well. For others, like alternative rock music, it provided a good grunt of meat, but at times closes in the song a bit more than I like, which for a genre that already suffers from the bad period of lack of dynamic range, makes it a bit more dark and missing some sparkle.

I loved how the MEST MK3 sounded on acoustic rock songs though. My endless plays of various progressive bluegrass and alt-country songs sounded well with this IEM. The fiddles, banjos and violins sound well controlled, with the added acoustic bass guitars and drums feeling heavy with good rumble.

Final Thoughts​

My recommendation for the MEST MK3 is to try different tips. This one can sound pretty different with what tips are thrown on them, as I had already discovered, but almost forgot about, with the original MEST MK1 and MK2 units. Once you find the one you like, I think the MK3 really shines and comes off as a very engaging and smooth listen, with good technical performance and a very warm and rich sound that is well-extended at the same time. It doesn't do a lot wrong, and is a great cohesive affair, and something that brings a new life to the MEST line.


Headphoneus Supremus
For SMSL DO300 in DACs
Pros: Lots of tuning choices
Remote Control
Easy to use menu
Good resolution and soundstage
Enjoyable sound signature with certain filter/color options
Cons: Same Design as Other SMSL Models

The DO300 is a new Digital-to-Analog Converter (DAC) from SMSL and it features the latest ESS flagship DAC chipset, the ES9039MSPRO. The unit comes in at a retail price at $549 and is available to order from our friends at Aoshida Audio. (

The product was provided by Aoshida for this review. As per usual, the review is my own set of impressions, and my link is unaffiliated.

I have recently reviewed the whole fleet of the SMSL DO and HO series DACs and headphone amplifiers, starting with the small and solid 100 series, and the middle 200 series. The 300 series, here, does not currently have a matching headphone amplifier, and I was told there are no current plans for a release of a HO300. That said, the HO200 should stack perfectly with the DO300. I still use the DO/HO100 series daily at work, as it has plenty of power and its compact size makes it a nice desktop compliment to my laptop and monitor for work use.


The DO300 has a similar look to the DO200. In fact, visually, its almost indistinguishable if it wasn't labeled with their model numbers. They both feature a small color screen on the right side, a multi-functional knob down the center, and the same set of input/output ports on the back, in the same exact locations.

This includes XLR and RCA outputs, and a variety of different inputs: AES, I2S, Coaxial, Optical/Toslink, and USB-A. In addition, there is a bluetooth antenna which has the latest Qualcomm Bluetooth 5.0 standard, and allows for LDAC, AptX-HD, AptX, AAC and SBC formats.

Under the hood, there are a few new upgrades. The biggest change is the aforementioned DAC chip. This SMSL unit is built upon the ES9039MSPRO DAC chipset, the newest flagship from ESS. In addition, the unit employs 11 op-amps for output to the RCA/XLR ports and eventually to your amplifier.

This unit also features MQA decoding support, and will light up blue or green when activated.

Firmware Features​

The color display can be controlled by the multi-functional volume knob, or with the included remote. I prefer navigating this with the remote, as it makes it quite a bit easier to use, as there are quite a bit of different options to play with.

The menu is the same as the DO200 MKII that I reviewed. Users can navigate through menus to change inputs, outputs, variable or fixed volume mode (preamp), jitter control (DPLL), dimmer, brightness, and most importantly to me -- PCM and DSD filters, and the SMSL's audio Sound Color menus.

The digital filters include 8 ESS Sabre filters to choose from:
  • Filter Off
  • Minimum Phase
  • Apodizing
  • Linear Fast
  • Linear Slow
  • Minimum Phase Fast
  • Minimum Phase Slow
  • Low Dispersion
The unique one that I don't remember seeing before is Filter Off. I didn't know you can disable over-sampling on a Delta-Sigma DAC, so this was an interesting one to see and to play with.

For the Sound Color menu, there's an addition series of filters:
  • Standard (off)
  • 3 Levels of Rich
  • 3 Levels of Tube
  • 3 Levels of Crystal
Each of these, I presume, plays around with EQ and phase to provide a different type of sound that was subtle, but distinguishable sometimes.

Sound Impressions​

For this review, I primarily listened with my Hifiman Susvara headphone through the Bakoon AMP-13R amplifier. My normal day-to-day DAC in this set-up is the Holo Audio Spring 3 KTE (with pre-amp module), which is an R-2R resistor ladder DAC as opposed to the Delta-Sigma chipset-based DO300 DAC I am reviewing here.

My high-level takeaway here is that I actually really enjoy using the DO300 DAC quite a bit. It presents an alternate listening experience to my more analog sounding Spring 3 KTE, and for being a more precise listen, the DO300, has a very smooth overall sound.

In many ways, going to a relatively lower budget DAC with a D/S chipset implementation can have a brighter and more sharper type of sound. This, of course, isn't always the case. I really enjoyed Audiolab's use of the old ES9018 DAC in their A6000, and found that they smoothed out all the glare issues normally found one of those older Sabre DACs.

With the DO300, there's a lot of play here that you can customize how you want the DAC to sound, with its selection of 8 filters and 10 coloring options. I found using Filter Off (No Oversampling) to be my favorite but I was perfectly happy with the traditional Linear Fast and Linear Slow filters too. For coloring options, one of the Rich or Tube, or default Off was quite enjoyable. The Crystal options made it sound, as you would expect, a little more bright and gives a sense of more detail, but at the expense of being a bit fatiguing.

The DO300 is very resolving, and clear, but does not have what I consider a sense of faux-clarity, where excessive treble/brightness makes details more forward and sharp. Instead, I found a sweet treble that I thought mixed well with the overall sound.

The DO300 is punchy, and layered. It's punchier than my Spring 3 KTE, which is a little more warm and soothing versus ultra-neutral. Characteristically, I find the differences are most apparent when you listen to how strings resonate, and even their base frequency note sounds different between the two. The Spring sounds natural, but slightly dampened in a way, but resonates more organically, while the DO300 has a more defined and incisive strike, with a resonance that also has this brighter hue to it that isn't quite digitized, but isn't also a warm, soothing fireplace feel either. It's a bit hard to fully describe these general differences between the R-2R and D/S sounds in just words, without listening to it.


SMSL's DO300 is a very nice DAC that makes use of the latest from ESS with their ES9039MS PRO DAC chipset. This little unit has a variety of sound tuning options within its simple and colorful display that is easy and intuitive to control with the included remote.

I was happy with the overall reference sound, with good resolution, punchy bass, and sweet and smooth treble. For a well-measuring, reference-type DAC, this one checks a lot of boxes for me in a small desktop-sized box.
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Headphoneus Supremus
Great Value Reference IEM
Pros: Great U-Shaped Tuning - matches my preferences
Relatively low price
Beautiful shell design
Outstanding CEMA cable included
Lightweight, comfortable fit
Cons: Not widely available
Bass decay a tad fast

The Supernova is a flagship in-ear monitor product from Indonesian boutique maker, 7th Acoustics. This product comes in at a small $750 USD price tag for a flagship, and has a total of 6-BA drivers in a nicely laid out package. The unit was sent to me by another review, Theo of Precogvision and fame, as part of a 7th Acoustics tour.

I had just published a review of the Proxima the other day, which is a neutral reference budget IEM from 7th Acoustics. This one is their top of the line model and takes the neutral tuning and adds a small bass shelf that puts it into my preferred territory, and matches it up directly with my beloved Hidition Viento "B" CIEM.

The Supernova comes in a taller round tin container than the Proxima, with a screw-on top. While this is secure and a nice touch, the metal screwing on metal can be grating at times, but not a big deal.

The Supernova comes with a very high-quality CEMA cable that I absolutely adore. It is a copper-colored braided cable with large 4.4mm pentaconn connectors on the source side, and 2-pin connectors on the IEM side. The 4.4mm connector has a striped gold and chrome/silver look that I really enjoy and matches the similarly styled Y-splitter.

7th Acoustics went with a very traditional universal IEM fit with a rounded triangular shape and a medium length nozzle. It's an easy fit for me and is very comfortable. The front faceplate has their logo above an abalone design. The one this unit came with is a blue/green look, but there are many other color options available on the company's Facebook page.

Sound Impressions​

As stated earlier, the Supernova adopts a balanced and mild U-Shaped tuning that is very well aligned to my target preferences. This has a small bass shelf that downward slopes into the mids, and a gentle rise in the upper-treble and a very smooth and extended treble range. The Supernova has a neutral-relaxing signature with added low-end warmth.

The sound signature of the Supernova is easy to comment on. It's good. I enjoy the balance throughout the frequency response, and the smooth sound that comes with it. It does not have any disjointed transitions, and is very coherent in general. I don't have a lot of to complain about in the tonality choices made here.

On the technical side, I also have little to complain about, especially at its relatively low $750 price tag, which falls many times lower than other brand flagships. Its even lower-priced than my Hidition Viento, and is going to compare well with the Thieaudio Monarch MK2 and Clairvoyance.

The Supernova has pretty good resolution. It doesn't exert all the minute details that I sometimes hear on the Empire Odin or the Unique Melody MEST, but I also don't feel like notes are smeared, and transients are overly rounded. In fact, I actually am a little surprised at how sharp notes can sound sometimes, however, knowing that this is an all-BA set makes a bit of sense.

Sound separation and soundstage in general is medium to wide for in-ears. I never felt the intimate and sometimes very forward and small sound of the Proxima, and there's plenty of space between instruments that makes listening to big orchestral pieces here sound decently grand. The Supernova also does a good job of providing depth, but it's not the best I've heard.

Comparison to the Hidition Viento B

When I first looked at the FR curve for the 7th Acoustics Supernova, I immediately thought of the Hidition Viento-B, my daily-driver CIEM. And measurements-wise, they are quite similar as shown above here. But they do differ a bit in overall sound performance.

First off, I find the Viento to be surprisingly warmer, but also a tad brighter. The warmer part was a bit surprising, based on the graph, but it could also be due to the totally perfect fit of a custom-fit versus a universal-fit of the Supernova.

The Supernova has a more quick response with crisper edges and a little more definition to certain notes. That's not to say it is more resolving than the Viento, it just means that the Viento has a longer decay and sustain-ability, which does not sound as exacting. Which is more natural? That's tough to say. I think the Viento comes across a little more natural, but the Supernova comes across more clean and technical in this aspect, with also a slightly wider soundstage in my listening.

In some ways, the Supernova is a more up-to-date Viento-B, and that's a good thing in my viewpoint, as again, the Viento is my ideal IEM, though sometimes seeing its age in the technical ability versus newer flagships. Both are also strong in coherency, and that is perhaps where I find the Viento a little better, but it really is a toss-up. Some people may not like the smooth sound of both of these, but I'd ask, why not?


Headphoneus Supremus
Pros: Great warmth and timbre
Good resolution
Excellent Build quality
Comfortable to wear despite weight
Fantastic with rock music
Pad Rolling Options to change tonality and technicalities
Cons: Not a lot - not as grand/open sounding as Hifiman planars

I've had the pleasure of an extended review loaner of the $3499+ ZMF Caldera that's been at times on my head and off-times off my head over the course of several months now. It is no fault of the Caldera at all, it just happened to be a rather busy period of holidays, being stricken with illness, recovering, traveling, and just a busy work schedule. But, every time I do reach out for the Caldera, it's been a nice, pleasurable listen that I am going to discuss more in this full review.

First off, I did provide my first few days of listening impressions way back in November prior to the headphone's launch. I was lucky to have been able to get my hands on the headphone to try out from Zach of ZMF himself, and have been holding on to it for quite some time, though sharing it with several members of the Seattle audio community in the months I've had this in my possession.

Each local audiophile auditioner loved what they heard, and I can go more on that later, as I did collect some notes to discuss.

The Headphone​

The ZMF Caldera is Zach's first foray into a custom-designed planar-magnetic driver. Previously, he started the ZMF company on the backs of modifications and improvements to the Fostex T50RP series of planar magnetic headphones. He introduced new internal mods, and his famous and unique wood-cup designs to the headphone and went through a few different iterations, before switching over to custom biodynamic driver-based headphones, and then the beryllium-based drivers of the Verite series.

The Caldera brings him full-circle back to his roots from 2011, when he made his first modded T50RP. The new design here is an 80mm planar driver that has an impedance of 60 ohms and headphone sensitivity of 95 dB/mW. It's not a hard to drive headphone, but it may push your portable gears to the other end of its volume limits than the beginning.

The unit that was sent to me is the standard Oak wood cups with black grills, rods, and chassis. This is the basic model, but as with all ZMF headphones, there are upgraded color and metal options, and limited edition wood runs that are very popular and always look stunning. As I am writing this now, there is a limited run of Bocote and Redheart woods available.

Each Caldera order comes with 2 sets of pads of your choice, and a cable with the termination of your choice. Every order is customized for you, and because each wood piece is unique, you'll get a surprise of how it looks when you open the box. Each one I've seen, in real-life or online, have been spectacular looking, and owning ZMF headphones previously, I've never been disappointed in quality of the build, or appearances of the wood pieces. The Caldera is no different.

The new headband design is more padded than ever and is designed in a way that makes the weight of the headphones feel much lighter than the scale will tell you. For most headphones over 450 grams, I typically feel the weight of them pretty quickly. This one scales at well over 500 grams, but it still feels comfortable for long listening sessions.

The pad options included in this set were the Caldera leather pads and the Suede pads, as well as a cowhide pad that was a bit thinner than the other two. The Caldera leather and suedes were on the thicker side, but are both very comfortable to wear. Each of these have their own unique sound characteristics that I will describe in the sound section later.

The cable included is the new ZMF standard headphone, which is a black-cloth sheathed copper cable comes terminated in the connector of your choice, and meets the headphones with the standard mini-XLR jacks that are normal on every ZMF headphone.


I primarily used the 1/4 inch cable with my listening sessions, although there was a balanced XLR cable available in this kit. I did try using that for quite a bit of time early on with my iBasso DX240 DAP, but for the most part, I used the standard unbalanced 1/4 inch cable with my Bakoon AMP-13R and Holo Spring 3 KTE set-up I use for headphones.

Sound Impressions​

Some of the following will be a bit of a re-hash of my prior impressions, but I'll try to add more detail and some sample impressions as I write this, along with some feedback from community members who have also had an opportunity to demo this specific set over the past few months.

The Caldera is a warm-tilted, and slightly-dark sounding headphone, but doesn't stray too far away from what I consider a neutral sound target, at least for a typical ZMF. It's easily the most traditional reference sounding headphone that I've tried in ZMF's lineup, but it also continues to feature a heavy dosage of the ZMF House Sound that has a warm and rich mid-range that is quite engaging and enjoyable, and a sweet treble range that is extended and smooth. The bass extends into the sub-bass fairly well, and is generally linear throughout with a little dip as you go further down to the sub-regions.

If someone took the tonal balance of an Audeze planar (e.g. LCD-4) and a Hifiman planar (e.g. Susvara), and split it down the middle, I'd say you'd land pretty close to what the ZMF Caldera sounds like. It takes the best parts of both, and gives a very well-balanced headphone in its tonality.

I enjoyed using the Caldera a lot with rock music. It's the stuff I grew up on and I always love listening to 90s alternative and this headphone does it quite well, and better than my "end-game" Hifiman Susvara. When I listen to Alice in Chains or Smashing Pumpkins, or even Radiohead or The Ataris, there's just more meat on the bones on a Caldera than a leaner, but more elegant Susvara. The Caldera has more body in the mids and a slightly darker treble range that eases off on the wailing guitars and crashing drums, and gives more thickness to vocals, bass guitars, and kick drums, that help give more raw power to these anthem tracks.

When I put on some Nickel Creek, and their brand of bluegrass music, I still found the Caldera to be quite enjoyable, with a good soundstage, imaging and instrument separation. The band's trio of string instruments sound defined, but don't necessarily have the crispness that they would sound on the Susvara, and trails just behind it on resolution for these very minute details such as the faint strings fading away in the background. But, the Caldera still does a commendable job on resolution and soundstage -- it's just not as open and resolving as the Hifiman flagship that also cost over 50% more.

In terms of planar magnetic headphones, the Caldera is one of the closest to a dynamic driver sound that I have heard. It's still "fast", but the weight of the notes, and the richness in its presentation, along with the longer decay give it a more natural sound than the typical Hifiman planar headphone that have stocked my collection through the years.


The pad material options do play a role and a fairly significant one here.

The standard leather Caldera pads have the most neutral sound of the three I had, and provides the most dynamics and punch. The transient speed felt the fastest here, and most intricate.

The suede Caldera pads offered a smoother sound, with a little less emphasis in the upper-midrange and low treble, and more rounded edges and slowing down the overall transient speed.

The cowhide pads are quite a bit thinner than the other two in size, and with this, made a very different sound presentation. I found this one darker in the upper-mids with a treble lift that is similar to the Verite series. I thought this still kept the snappiness of the leather pads, but also gave a more holographic soundstage, but with a much more wonky tonal balance that I liked the least.

More Listening Impressions​

I took these out to a couple audio meets in the Seattle-area over the winter months, post-pandemic, and had a few people I met in the community try them out. For the most part, I think everyone enjoyed what they heard, with some seriously contemplating buying them. Some compared these to the Atrium, another ZMF headphone with a similar tonal balance, but in a dynamic driver configuration.

The Atrium is one of my favorite headphones, and I absolutely loved using them for rock music when I had them on loan from ZMF when they first came out. They were my favorite ZMF at the time, and now the Caldera has surpassed them for me, because the Caldera improves the resolution and its tonality fits my preferences more.

But that said, there were folks who preferred the dynamic driver sound on the Atrium over the planar sound on the Caldera. The Atrium is a little bit richer with a stronger note presentation and longer decay. It's ever slightly darker, and so there were people who preferred this thicker and more relaxing presentation over the Caldera.

There was another listener who really loved the Caldera and has been contemplating buying one for a while now, as an upgrade to the Hifiman HE-6. When this person first listened to it, he thought it was good with the Caldera leather pads, and was already thrilled with it. Then we swapped out the pads with the Suede pads and I quickly observed his smile grow as he listened to them. It seemed like a serious "A-Ha!" moment had occurred! At the time of writing this, he was still deciding whether to buy this headphone or not, but hopefully he'll get to demo this set again in a couple weeks and go from there.

Like I said, of the dozen or so people who tried it, I didn't see or hear any dislikes or even "so-sos". Everyone seemed to enjoy the Caldera. Some still preferred the sound of a dynamic headphone and leaned toward the Atrium or Verite, but all of them really enjoyed that ZMF sound, despite other top end headphones around.

For me, I don't necessarily care one way other the other if it's a dynamic or if its a planar. There's some characteristics that help kind of define the sound of the two, but I find that that is changing as we evolve headphone technology anyway. The Caldera has a lot of carry-over sound that reminds me of a ZMF dynamic headphone, more-so than most other planars. It is a great in-between, and does so with a good all-arounder sound.

Final Thoughts​

The Caldera is a great headphone. It has the ZMF DNA in it -- wonderful wood aesthetics, solid build quality, top notch customer service, and the typical warm and lush, engaging mid-range I've come to expect from their products. For folks that had hesitation on ZMF's tonality in the past, this one, along with the previous release, Atrium, should help provide a different outlook -- it sure did for me, despite being owners of other ZMF gears in the past.
Just replace of "seriously contemplating buying them" with "dreaming of someday owning one" and you got me :smile: Great review!


Headphoneus Supremus
Pros: Feature-Rich product
Good build quality
Clean, neutral sound signature
Cons: Amp Hiss without IEMatch Enabled
IEMatch may change FR of some IEMs
Hard to read text
Expensive for dongle dac

Several months ago, I did a Dongle Discourse Shoot-Out and I crowned the Cayin RU-6 my champion at the time. While, I still consider it my favorite dongle of that batch, I wanted to re-visit some of these dongles a bit more, and today I will take a deeper look at the iFi Go Bar, a very popular and pricey $349 USB-C portable DAC/Amp that is full of features, and my opinion of it has changed a bit since then.

The iFi Go Bar I am reviewing is actually from and was sent to me from Precogvision of their team many months ago, but I still have it here for now.


For this premium dongle, iFi included a very nice leather case that can carry both the unit and the USB cable(s). The unit comes with both a USB-C to USB-C cable, as well as a USB-C to Lightning cable, along with a USB-C to USB-A adapter. This should fit most use cases for digital transports, whether that be a computer, laptop, tablets, an Android phone or an iPhone.

Buttons & Features​

The iFi Go Bar has a couple features that are controlled with 3 side buttons. First off, you can control volume with the two volume controls, and the third button switches between X-Space, X-Bass+, both of them on, or both of them off. The default is off.

Holding the third button, and then using the volume controls will toggle through the various filters iFi has put into the Go Bar. This is a nice feature that was lacking on some of the other iFi products, and required firmware rolling to change digital filters, if that was even an option.

I also prefer this option because I haven't been a fan of iFi's preferred Gibbs Transient Optimized Digital Filter, aka the GTO Filter. The GTO filter reduces the taps in total, making it a short filter, and minimizes the pre and post-ringing, while also being asymmetrical. Typically, most DACs default to a symmetric filter with both pre- and post-ringing with a steep cut-off. What is best is sort of up to the user to decide.

While the features are abundant for a small little dongle DAC, I am not a big fan of how to determine what settings you are on. Over time, you can memorize or just remember what things once you get the hang of it, but the tiny LED dots, and the tiny text is already likely hard to read, but then you add in the fact that they chose a light grayish-blue (periwinkle?) text color on top of a dark gunmetal gray shell design, makes it exponentially harder to read, no matter how much light, what angle its coming from, or how much you squint. It's barely legible, if at all for me, as someone who doesn't require eyeglasses for anything.

In addition to the main buttons, there is also a toggle switch that enables the iFi IEMatch, which attenuates the sound and adds a small impedance gain to the circuit to help reduce noise from the amp. I am going to go on a quick soapbox here, because iFi could, you know, just make their default circuitry less noisy, but they choose not to. At least in this case, they added IEMatch to the setup, instead of making you buy their rather overpriced standalone attenuators. But, if you use output impedance-sensitive IEMs, typically ones with multi-BA setups and high sensitivity, you may run into problems with the tonality of your IEM changing with the extra impedance added. For many IEMs, it could be nothing or minimal, but some products from Vision Ears or Campfire can be rather drastic changes in either bass, treble, or both.

Sound Impressions​

For sound, I primarily used this product attached to my laptop and used Roon as the software source, playing both local files and music streamed from Qobuz and Tidal via Roon. For IEMs, I used a variety of different products like the Empire Ears Odin, Hidition Viento, Xenns Mangird Top, UM Mest, and the 7th Acoustics Supernova, among others. I also used it with the Sennheiser HD600 headphones. For all cases, I stuck to 4.4mm balanced for output.

Quickly going back to the IEMatch and amp noise. Yes, the Go Bar can be noisy. There was audible hiss on many of my IEMs when I had audio active, and in quieter parts of music or general playback. It was a bit annoying, but this wasn't a problem with the Sennheiser HD600. I tried to stray away from using IEMatch because some of my IEMs may be sensitive to changes in impedance.

Using the iFi GTO filter (white LED), I found the sound rather bright and a bit digitized when listening to Mipso's self-titled release. Switching filters while playing music was rather simple, and quick, and surprisingly, I felt going to any of the other filters provided gave a more warm and enjoyable listen - whether that be the standard linear filter, the minimum phase filter, or the "bit-perfect" filter (no digital filtering).

I stuck with the linear filter, as that's the most standard for the rest of my listening along with the HD600 headphone, since using IEMs gave an audible hissing noise.

For the most part, the Go Bar doesn't do anything wrong. It's quite neutral sounding to my ears, with no real emphasis in any part of the spectrum, unless you enable one of the digital processing effects. XBass+ gives a big boost to the bass region, with what I believe is a +10dB down-sloping curve through the bass region.

The XSpace plays with phase and cross-feed to give a more 3D-ish holographic sound, but does make the overall sound much more lean and seemingly strange. Adding both effects enabled provides a better tonal balance and gives a slightly larger soundstage, and is what I'd recommend using for brighter headphones.

With that said, I preferred sticking it out without the effects on. And with that I found the iFi Go Bar to provide a clean, and resolving playback presentation, and perhaps the best iFi portable presentation I heard yet -- all from memory of course. While soundstage wasn't large and more intimate without XSpace enabled, I didn't find it glaring or too forward that it became a claustrophobic mess. Technically, it handles busy passages and simple ones quite well, and outside of the noise issues and preference of filters, I don't have any negatives to say about its sound.


The Go Bar is every bit iFi in my opinion. It packs a lot of features and is built pretty well. Unfortunately, as many iFi portable products have, it makes a lot of amp noise that is audible in higher sensitive products like many IEMs, which can be a killer. Luckily, this product does include the attenuating IEMatch feature, although it can also change the frequency response of some IEMs when enabled.

With that in mind, it does work well, and has enough features that sets it apart from the crowded dongle space, but it is also the most expensive that I am aware of on the market, making it a bit hard to recommend overall.


Headphoneus Supremus
Pros: Good value with a unique sound
Pairs well with brighter headphones/iems
Silent noise floor in my trials
Unique colorway that looks great
Cons: Darker sound may not be for everyone
The unique gunmetal color doesn't match with other Schiit gear
Less power than standard Magni series

*note: the volume knob has been replaced with a larger gold-colored knob as shown in this photo

The Piety is a custom run of a previously prototype design of a Magni by Schiit that was taken by longtime audio community member CeeTee and produced by hand on a small-scale with his own branding, Nitsch. This Piety borrows some of its Continuity circuit amplifier topology from Schiit's Jotunheim 2, but in a much smaller form factor.

One of the reasons Schiit never took this specific design to market was due to a shortage on some of the parts, as they were no longer being produced. That allowed CeeTee to do a limited run with the scarce parts available and make this somewhat of a rare collector's item headphone amplifier.

The Piety shares the same chassis and exterior looks of the Magni series that Schiit is probably most famous for. It blends the black and silver options of the sibling product into a Gunmetal gray finish that makes the Piety stand out a little bit more unique than the Schiit line. There is also a square Nitsch logo on the top corner of the amp.

The Piety does not offer quite as much power as the other Magni amplifiers, but it does supply adequate power for the majority of headphones on the market, with only some challenges with the most difficult to drive planar headphones in my experience. I had no issues with headphones like the Sennheiser HD600 series, or any IEM I threw at it, and it worked well with the ZMF Caldera. It struggled a little bit more with my Hifiman HE400SE and Susvara.

With IEMs, there was surprisingly no noise floor issues at all. I've had hit or miss experiences with Schiit products on this front, and the Jotunheim 2, for example, had some audible noise with some of my IEMs. The Asgard 3 did not however, and neither does the Piety.

Speaking of the Asgard 3, I would think that this was the most similar characteristics of the Schiit amps I've tried/owned and remember hearing. I did not have any Schiit amps to compare to directly, but I had owned the Asgard 3 for quite a while and really enjoyed it for its warm and pleasant sound, and the fact it had a very, very low noise floor. The Jotunheim 2 was a bit brighter but very punchy, and despite sharing the same topography, I did not find these two similar at all, from reviewing my notes.

Sound Impressions​

The Piety is marketed as a Triode-like sound. For those unfamiliar with what this may mean, its representative of a tube-amp sound, while still being a solid-state. For the most part, I can see why the marketing print states this, and early listening impressions provided such statements.

With every IEM and headphone I threw at it, and with my primary listening coming off of the Empire Ears Odin and Hidition Viento IEMs, I found the Piety to be quite a bit darker, warmer, "slower", and rounder than my other gear. This type of description can be what you may hear on what a typical tube amp could sound like, however not all tube amps I've heard are necessarily dark. Some can be bright too, however, but that's for another day.

The Piety, when compared to a typical op-amp based solid-state, sounds quite unique. I spent some time comparing it to the SMSL C200 DAC/Amp, as well as my iBasso P5 Falcon portable amplifier, which I've modified with a custom configuration of op-amps (TI OPA1622, MUSES 02, and a pair of Burson V5i discrete op-amps).

The C200 gave the most precise and probably most in your face sound of the three. The customized P5 had a nice gentle and smooth treble with a wide soundstage, but felt open and grand, while still having quick transients and precision sound. The Piety was quite noticeably darker with slower progressions. It had a soundstage in-between the two, and a much thicker sound.

The Piety works as advertised I'd say. It gives users a different sound that is unlike others that I have found in this price range, with a darker, thicker, and more lush sound. It lacks on power, but should work well with most headphones. I found the crazy warm-warm pairing of an R-2R DAC and the Piety to work quite well surprisingly, but its definitely something I think users would enjoy with neutral and brighter headphones, and it may be just too warm-bodied for already darker headphones.
Where's the knob from? Would like to find one in another colorway 🤭
I bought it on Amazon


Headphoneus Supremus
Pros: Excellent reference tuning
Top end resolution and speed
Comfortable and lightweight
Cons: Some may find it a tad lean
Source-dependent ($$)
Cable is pretty poor for a TOTL flagship

The Hifiman Susvara was once quite ridiculed and hated for its outrageous price tag at its time at $6000. Yes, that's right, it's $6K. And it still is today, 6+ years later. And while it's still one of the most expensive headphones on the market, there are others in this price range now that compete with it, including even more expensive in-ear monitors!

Some of the vitriol against this was the entertaining video interview between Tyll Hertens and Fang Bian, the owner of Hifiman, and also Hifiman's long-going quality issues and relatively lack-luster build quality for their asking price. It's true, the company focuses primarily on its driver technology and its stellar tuning, and sometimes slaps it together in whatever form-factor that'll work.

After always dreaming about this headphone, I decided to just sell off the majority of my headphones and audio collection except a few essentials and just buy up this unit. I've always wanted to get my hands on this unit, being a long-time fan of Hifiman's tuning and lightweight designs, despite fragile they can be sometimes.

So, it was to my surprise that the Susvara's build is actually not that bad. It shares similar designs with my previous two Hifiman staples: the HE560 and the Arya, and can actually be considered a smashing of the two. It's not quite round, and it's not tear-dropped either. It's kind of an oblong-circular cup design with the same style headband as my two prior headphones. The headband removes the plastic yokes and has full-metal headband and yoke design that feels very strong and sturdy. The grills are aluminum and don't have any issues with creaking or feel like they're going to implode on themselves.

There is still the goofy wood veneer from the HE560 though. It's not the best, but it is not appalling either. I'll take it.

The Susvara nano-scale diaphragm and magnet structure were its major selling point, allowing it to have major improvements in resolution and clarity, as well as what I'd say better tactility and impact. One thing that was interesting when this headphone came out was that the majority of Hifiman's releases were moving more and more towards efficiency and allowing their planars to be played on a variety of sources. The Susvara goes backwards a bit in this movement, and has power requirements more akin to their old HE6 model, with a rated sensitivty of 83dB/mW and 60 ohm impedance.

This means, you'll need an amp with at least 2 Watts into 60 ohms to really get the best out of the Susvara, and for the most part, I think this is quite true. I've run this on a gambit of sources and the ones with the most power seem to really show off the most characteristic features of the Susvara the best, with my current pick being a 50 Watt (into 8 Ohm) integrated speaker amplifier using the speaker taps as my headphone connection.

Before I go further into the sound qualities, I do want to mention that the Susvara's unboxing experience was kind of lackluster for the $6000 MSRP tag. It came in a latched box, which was alright, but did not include a portable travel case, and the cables are horrendous. They're the same ones that come with the HE6SE V2, HE1000SE and a few other recent headphones.

Hifiman did include a hardcover photo book detailing the features and process of designing the headphone, which is a pretty nice coffee table item.

So apparently, I started writing this review in May 2021, and I stopped my writing at this point in time. It was so long ago, I forgot I had even wrote anything. I tend to be slower or sometimes never get to reviewing products I own, but anyway.... Since, it seemed like nothing really changed, I will continue writing the review from where I left off, nearly 2 years later in March 2023 now...

Sound Impressions​

The Susvara is my favorite headphone. I've owned it for over 2 years now, and I've tried many other headphones before and after that point, and it's still the one I go back to. The Susvara has a very neutral reference sound that doesn't color anything. It's not as bright as your typical Hifiman, as it doesn't have any random peaks in the treble range, and it doesn't have a large dip in the mids as some planars do. The bass levels are flat from the lowest sub-bass regions through the mids, and begins to rise just after 1KHz, and extends well into the upper treble range, giving this a nice clean sound that doesn't exaggerate any one frequency range in my opinion.

Before I dive further into this, some may have read my adventures in amping the Hifiman HE6SE V2, and going deep down the headphones and speaker amp rabbit hole with it. I ended up with a Bakoon AMP-13R after all was said and done, which is a 25 watt (into 8 ohms) speaker/headphone amp that was designed from the ground up around the Susvara, and it shows. It's a perfect pairing, with a warm-bodied sound compliments the neutral sound of the headphone.

So, yes, the Susvara requires some power to get going. It will drain your digital audio players, and will require you to push them to their limits to get it up to listenable volumes. When I tried it on a Chord Mojo, for example, I drained the entire battery of it in 25 minutes. My iBasso DX240 audio player can get it loud, but bass performance was severely lacking. And, basically, don't even try it out of an Apple dongle.

Using the Susvara dropped me deeper into the DAC rabbit hole too. I settled in with the Holo Spring 3 KTE at some point, and now my chain starts with Roon, through the Holo Spring 3 KTE DAC, and finally into the Bakoon AMP-13R, where spits audio into my ears via the Susvara. And for the most part, it is ultra bliss.

The Susvara is source dependent. I mentioned this with the HE6SE V2, and the same can really be said with this one. If you put a bright setup with it, it'll be bright. If you put a warm source behind it, it'll be warmer. But in all cases, it's still fairly neutral in its overall tonal presentation.

This headphone really excels at resolution. It's a detail monster, and it presents it in a very open and large soundstage that is layered with texture and micro-details when called upon. The bass presentation is nuanced and fast, and is unlike many other headphones I've tried. It doesn't necessarily have the long, lingering decay of a good dynamic driver, but it can slam with the best of them -- if you give it the current it needs to give you the volume and drive it takes.

On the morning that I'm writing this out, I'm jamming to Nickel Creek's latest record, Celebrants. It's a progressive bluegrass record that truly excels on Susvara. Acoustic music is one of the specialties that I feel Hifiman made shine on their creation. The intricacies of each instrument are on full display, with a large and grand soundstage, and quick, exacting detail projected to each of my ears. The sheer speed and agility of the string-play the band presents can be fully appreciated on the Susvara, because its driver can keep up and then some.

I've had Hifiman headphones from their entry level up to this flagship in the past, and when I compare say the entry level HE400SE or the HE6SE V2 to the Susvara, I can quickly discern the differences in sheer speed of the driver. The faster transients that I hear make a big difference in how resolving the headphones sound, and while I adore and use the HE400SE quite often (it's my work-office headphone), I can easily hear the resolving deficiencies between this entry level headphone and the Hifiman flagship.

I put on a more upbeat, but, still acoustic album, Mipso's self-titled record from 2020, and listening to songs like the faster-paced "Hourglass" sound wonderful on Susvara. The bassline hits well, and the snare drum is timely and not distracting. It falls behind the scene as it should, and let the vocals shine. The lead guitar and bass guitar intro of "Your Body" sound very coherent and balanced, while Libby Rodenbough's sometimes breathy and strained-sounding vocals are so full of detail, that you can hear the transitions between the loud and quiet singing quite well and without skipping a beat.

Now, I will say, some may find the Susvara a tad bright, or perhaps too neutral. And there is some truth to that. It's definitely not very colored, and may not have as much warm body as other headphones that people tend to compare this too, such as a typical Audeze planar, or a ZMF headphone -- both of which have warmer mids, darker treble, and a fuller-bodied sound. These are their house sounds, and Hifiman has always strayed towards a less colored, and sometimes bright-tilting tonal balance.

For alternative rock and hip hop music, I still find the Susvara enjoyable, but perhaps this isn't its strongest suit. For me, these genres could use the extra mid-bass or mid-range body, or perhaps a little darker skew to the treble range that tames some of the electric guitars or electronic treble-inducing beats. And in that case, I prefer listening with the fantastic ZMF Caldera, another planar open-back headphone with a more warm and fuller tuning.

Even so, putting on Radiohead's The Bends is still a treat. It's can be a tad bright at times with the amount of electric guitar and high hats going on in the busiest parts, but that depth and layering qualities the Susvara can present is really something -- and a band like Radiohead, who is all about those intricate details in every one of their songs -- its not a bad thing at all. "Everything in its Right Place", for example, sounds incredibly large, awe-inducing, and hypnotizing on this headphone.

Final Thoughts​

I could probably write more and more about this headphone, but at some point I do need to stop. While I don't think its probably the be-all-end-all headphone for everyone, it is for me and my musical preferences. I love this headphone for jazz, for bluegrass, for acoustic music. I enjoy it for electronic and classical, and rock. I don't know if I'd like it for hip hop, modern pop, and soul music as much, but I have other gear for that.

Obviously, this is an EXPENSIVE headphone, and it more than likely requires an EXPENSIVE set of sources (DAC and amp), which adds more to the cost, and so "easily recommending it" is not something I am going to do. But, this headphone does give me so much enjoyment listening to it that I find its value proposition still kind of ridiculous at times, but perhaps I justify to myself that it is an investment in quality and quantity -- and by quantity, I mean years of service. This is a for-life headphone, and not likely one that will be replaced. It's been on the market for 8 years now, and still popular and still being purchased today.

With that said, and a random note, my other "most-used" headphone is nearing its 27 or 28th year now -- the Sennheiser HD600. I haven't had it for that long, of course, but it is something to say that the two headphones I use the most are not just flavors of the month, and they've, so far, tested the passage of time with flying colors.
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Headphoneus Supremus
Pros: Great box presentation, cable, build
Extremely comfortable fit
Enjoyable tonal presentation
Good All-Arounder
Best YUME of them all
Cons: Small soundstage
Bass presentation quality average

When the original Yume came out from SeeAudio, I was very excited to see an in-ear that nearly matched my "Antdroid Target Curve." Of course, I did do a little bit of modification to it since then, but it still closely aligns to it, with the major difference being a little lack of upper-treble extension. But FR alignment wasn't everything, as I found the Yume to have an overall mushy and rounded-transients presentation that made it sound a little sluggish and below average in technical performance for its price point, and ended up giving it a mostly average to above-average score.

Not too long later, SeeAudio came back with an updated model with the backing of famous reviewer Crinacle and his tuning consultation. The Yume Midnight had improved in extension, with a little bit of a warmer and thicker sound, and overall improved tonality, but still lacked the technical chops to make it stand out in its price range. It still presented top notch tonal balance, but its limited technical capabilities made it only a slight improvement over the original.

Now, a year or so later, the Yume 2 is in my hands thanks to a review sample provided by Linsoul. This 2nd generation model features a single dynamic driver, and 2 balanced armature drivers and retails for $199 at (

Unboxing Experience​

The Yume box is a navy blue of sorts and a Yume female mascot graces the top of the box. Inside, you'll be greeted with a white SeeAudio jewelry box which houses the Yume 2 in-ears and the really nice and beautiful white braided cable. Inside the box, there are also a variety of tips and accessories.

The jewel box presentation is pretty clean. It is simple, yet elegant and the box is soft and padded and comfortable to carry. The inside has a little button tie-down to hold the cable down to, and is lined with a padded felt material which protects the aluminum housings on the Yume 2.

The cable is extremely lightweight, wonderfully simple and modern-looking, and does not tangle and maneuvers easily. There is a little bit of retained spring-memory, but I did not find it bothersome in my usage. The connectors terminate in 2-pin to the IEM, and 3.5mm to your music source.

The Yume 2 shells are aluminum metal with a polished mirror look. There is a inscribed yellow flower design at the center of each front faceplate. It is an attractive look that I think many will enjoy. The shells are also very small, light, and fit wonderfully. No pain or concerns for my ears.

Sound Impressions​

The Yume 2 is a very well-balanced IEM with U-Shaped tonal balance -- slightly warm bass and mids, and an even and relaxed upper-midrange and treble, with extension in the upper range.

The frequency response between the Yume series is quite similar across the board. The original Yume has the least mid-to-upper bass, with a more sub-bass focus, while also have the least treble extension. The Yume Midnight and Yume 2 have practically the same bass and mid-range, but differ slightly in the upper-mids, with the Yume 2 have a little more upper treble. Overall, the Yume 2 takes the best parts of both predecessors and increases the treble range making this the most well-rounded of the series.

Tonality aside, I found the Yume 2 to have improved technical response than its predecessors. When I compare it to the competing Moondrop single dynamic driver IEM products, I find that the Yume 2 to have faster transients, and wider soundstage. It also sounds a little leaner and less intiamate than say the Moondrop Kato or the Aria.

The Yume 2 still has a very forward sound, and has a few flaws pop out when the volume is increased. The bass response is quick and agile, but does not have a lot slow decay that makes it sound natural either. It decays a little too fast for my liking.

Due to its forward sound staging, I feel like it lacks depth and separation can be a little dense at times, but for the most part, it works. It's an intimate listen, and that's alright for most things.

Final Remarks​

The Yume 2 is a solid refresh for the series. It improves the tonality by taking the best of the series and adding more treble extension. The design is fresh and clean, and is very easy to wear and to look at when not in your ears. Its limited only by its bass performance being a little lacking and it being a little more on the intimate side of staging, but still an improvement in technical performance over previous generations.

This is a solid buy when comparing it to its price range competition and SeeAudio taking on Moondrop at their own tuning game and besting them perhaps for the same price point.


Headphoneus Supremus
Pros: Clean, and Accurate Sound Representation
Color display
Cons: Not a fan of the front-facing exposed fasteners

The DO200 MK II is the successor and a new DAC from SMSL which features dual ESS ES9068AS DAC chipsets and retails for $469 on Aoshida Audio's website. I personally never had an opportunity to try out the original DO200 DAC, so this is a new experience for me, but I am quite familiar with SMSL DACs and headphone amps from owning and reviewing many, many of them in the past.

This review unit was provided by Aoshida Audio and you can find the DAC here:

This DAC is medium-sized -- still small enough to put on a desk, but it wouldn't look too tiny on a shelf either. It's roughly the size or slightly smaller than that of the Topping A90/D90, or the Schiit Asgard/Bifrost/Jotunheim. Despite the small footprint, this DAC has a lot of input/output options for users to choose from.

The rear of the unit has both balanced XLR and single-ended RCA outputs to feed an external amplifier or speakers. The central input section has options for USB, Toslink Optical, Digital Coax, and the less common AES and I2S input connections. There is also a screw-on bluetooth antenna attachment included that provides a wireless connection from your bluetooth devices.

There is a main power switch on the back that cuts power completely, and pressing in the function button on the front of the unit turns on and off the unit from standby. The multi-function knob also controls volume and scrolls through the various menu options. There is also a remote control for easier use included.

One of the new visual items this unit has that I have not seen on other SMSL products is a new menu interface on the display. It's a much more colorful, and easier to see display. It's easier to use as well and lets you control a lot of options from the input/output selections, the digital filters, and other unit options.

General Sound Impressions​

The SMSL DO200 MK II is a very detail-rich DAC that sounds more exacting than rich and warm. Its not overly analytical like some DACs that may have this description and I don't find it overly bright on my choice of amps.

For my listening, I mainly used the Bakoon AMP-13R with it, which I find as a warmer than neutral source. I also used it briefly fed to the iBasso P5 portable amplifier when used with IEMs. For headphones, I mixed between the Hifiman Susvara, the ZMF Caldera, and the Sennheiser HD600 for listening.

One sound that I enjoyed a lot was Mipso's Hey, Coyote. This is a very gentle, acoustic song with an airy nature to it and both male and female backing vocals in a progressive bluegrass folk sound. The notes come off very crisp and clean. The plucks on the combination of fiddle, mandolin, and guitar are very gentle and defined at the same time. I enjoy this definition and exactness in a song like this where each acoustic instrument can express their own character clearly and free from embellishment.

DACs are a pretty hard thing to discern differences from in my cases, and it becomes a little harder when you are comparing chipset to chipset based DACs. My main DAC, however, is an R-2R-based DAC which uses resistors ladders and produces a unique sound that is different.

When I compare the SMSL DO200 MK II to the Holo Spring 3, I found that the Spring 3 had a bit more of an engaging and rounded sound, that was slightly warmer, and deeper in its texture capability. The Spring 3 had a more natural resonance to it, while the DO200 MK II sounded crisper, cleaner, and in some ways, flatter, in this not very apples to apples comparison in many regards (chipset, price, etc.).

I also compared the DO200 MK II to the other SMSL DAC I received, the DO100, which is quite a bit smaller, and half the cost. In this case, the DO200 MK II sounded just slightly more refined, though the differences were not night and day at all.

In many ways, they sounded quite similar, and in this regard, the differences in price and size is more geared towards having more plentiful options for input choices, and an easier to navigate and colorful menu system that looks better than just a simple white OLED screen.


Headphoneus Supremus
Pros: Great value
Good fun tuning
Punch bass and good resolution for price
Cons: Slightly bright upper mids
Cable is a little heavy

The S12 is LetShuoer's new and first planar in-ear monitor and comes in at $149 USD. This IEM packs a large 14.8mm planar magnetic driver encased in a all-metal shell and comes with a fancy multi-colored braided cable and a tin case. It's quite a decent package all together and it has a nice resolving and clean sound that should please many.

First off, I'd like to thank Joseph from LetShuoer for reaching out and sending me a review unit of this new product. As some may know from reading my past reviews, I'm not always the biggest fan of Shuoer's previous products, in fact many of them rank in quite the lowest tiers of my ranking list, but the recent EJ07M and this product is starting to change my opinion of this brand with a new name.

So let's just get down to business.

The S12 is a really nice sounding planar. A couple months ago, I reviewed the Timeless planar IEM from 7Hz, and gave the $219 IEM a rave review with some of the best commentary feedback I could give at the price point. Driver-wise, these two are similar in size but the S12 goes a step larger and increases the driver from 14.2mm to 14.8mm. Now, I don't know if these are similar drivers at all, or made in the same factory, but the driver plus tuning combination between the two IEMs are quite similar and very enjoyable.

Unfortunately during this review period of the S12, I did not have the Timeless on hand. I had lent it out to another reviewer, ufospl2 of Headphones-N-Stuff, for an extended listen on holiday, and so he's out there, somewhere, enjoying that set. Instead, I'll just have to manage this written review without that crucial A-B comparison, at least in the near term.

The S12 presents a small bass-boosted take on a balanced/neutral sound, that is right up my alley on tuning preferences. The mid-range is just slightly recessed with forward upper-mids and a generally smooth treble for me, however, some could find a slightly excess energy peak in the treble range, depending on how deep of a fit you can manage. There is also a nicely extended treble which helps with percussions and strings.

Many of the same characteristics I wrote about in the Timeless review can probably be brought over to here, but one of the key differences (from memory of course) is that I find the S12 just a little smoother, a little warmer, and with an extra amount of sub-bass rumble. These are things that I do not really think I mentioned in my Timeless review, but I can write here.

I never found the S12 to have the occasional bright glare on random tracks either, and I played this through a gauntlet of acoustical tracks from country to bluegrass to folksy music to female pop songs. The S12 handled them all quite well and with a good amount of "fun" for my tastes.

The tonal balance of the S12 is really solid in my opinion, however it doesn't have the fastest planar-like transient speeds. It's not quite the same speed and precision as my Hifiman Susvara, and is more along the lines of the Hifiman HE400SE, which is actually a very similarly priced $149 headphone. That is, while there is a decent amount of quality and resolution for this price tag, I don't think the precision is there. There isn't that extra layer of detail or exacting edge to each note that makes a higher tier driver or IEM stand out. It's not necessarily blunted, or blobby, either. It's just good, but not great or exceptional.

In addition, I find the S12 to have a relatively small and condensed sound. It's not grand and majestic, but provides a more intimate soundstage and more up and center presentation. While I don't mind this and it's never claustrophobic, I do like a wide and open soundstage personally, and this does not quite hit that mark.

But, all and all, I find these little things to be rather small in negative points when you take a look at what you're getting for $149. This is a very nicely put together package of build quality, accessories, and great tuning and above average sound. LetShuoer did a very nice job here, and they hit it home with great values in the last two IEMs I've tried. Things are changing for the better with this brand!
DJ Core
DJ Core
Love these. Perfect Tips to make 'em shine are the azla sednaearfit xelastec in ML size


Headphoneus Supremus
Pros: Balanced tuning
Comfortable to wear
Accessories and cable are good
Cons: Average technical qualities for price
Lacks depth of resolution
May find better products at lower price

The Mangird Tea came out a while back with some positive reviews and a decently pleasant overall sound. I personally enjoyed using it for its warm and somewhat too polite sound. It lacked a bit of air and treble, but the overall mid-range and bass was on point. Fast forward to now, and Mangird has rebranded to XENNS, but still also carries the Mangird name. Confusing, I know. But the Tea 2 is their new product with XENNS packaging, and Mangird on the faceplate. Luckily, its a good sounding IEM and let's dive a bit more into it!

First - Linsoul did provide me this review unit. It retails for $349 and can be found here:


The Tea 2 comes with a silver-colored braided cable with 2-pin connectors which is pretty nice to use and easy to handle. It's soft, and doesnt tangle easily, which is a bonus.

The faux-leather jewelry box is clean and attractive, and it has plenty of space for the IEM, with cables attached, a little mesh pocket for tips or small accessories.

The Tea 2, itself, is a comfortable-fitting, acrylic-resin IEM with a barely-translucent black finish, and a very subtle, yet attractive faceplate with varying shades of blue reflective flakes across it. The branding, "Mangird" is written in cursive across the faceplate, though it's not tacky in anyway.

Sound Impressions​

The Tea 2 takes a lot of the same sound signature of the original Tea, but adds more quantity in the upper midrange and lower treble region to give this Tea 2 set a much more balanced sound, whereas I found the original Tea to be tasteful, but a little dark and muted. The general sound is very appealing to my ears, and falls closely along what my preference target curve is.

The bass levels on the Tea 2 are quiet nice. I like that it is warm-tilted, but not muddy, and focuses more on sub-bass. That said, the bass quality isn't the best at this price range, and does come off across as rounded, and missing an extra layer or two of depth. For example, when I listen to Bill Laurance Trio's live version of the Pines, the stand-up bass guitar is just one-noted, and missing details. In "Signal in the Noise" by GoGo Penguin, the kick drum intro is more of a thud sound that something with expression. The overall quantity is really quite nice, however, and in most listening, I do value tonal balance over quality.

The mid-range extending up to the upper-mids is vastly improved over the Tea in my opinion. There is now no veil and not a dark sensation I got with the original Tea. The quantity here is perfectly fine and ideal. Perhaps there could be a bit more in the lower treble region to increase the dynamics and air to the overall sound, but that may lose the general "Tea" sound of being a warm, and comfy, cushy sound.

In general, I find the Tea 2 to exhibit a really solid balance of bass, mids and treble. Perhaps, a little more treble would improve its sound a tad, but there's not a lot to really complain about here. The technical performance is average for its going price of $350, but it is still a solid contender and improved quite a bit over the original Tea. All of that said, given its price, it'll find stiff competition from more technically gifted and similar tonality in the Moondrop Blessing 2 series, the 7Hz Timeless, and the S12 from LetShuoer.

Is humble details resolution related to humble (below Harman) presence 2-6KHz range response? Or.. what? Distortions?


Headphoneus Supremus
Pros: Comfortable shell design
Fun V-shaped sound signature
Nice cable and shell color styling
Cons: Bloated bass response
Upper-mids can be harsh

The TTROMSO is a new IEM by Tipsy that is named, incorrectly, after the Norwegian town of Tromsø. The theme around the IEM is based on the Aurora Borealis, I'm presuming, with its color pattern and design. The IEM retails for $89, and is a single dynamic driver in-ear with a V-shaped sound.

The TTROMSO was provided for review by Linsoul, and can be found on their retail store at The unit comes in a single color choice of PineStone Sea blue/green, and has a matching blue-colored IEM cable with fabric sheathing. It does get tangled fairly easily, but is otherwise extremely lightweight and comfortable.

The shell has a sea-green and blue look, with something of a borealis or ocean/algae look. I can't really tell for sure. That said, this is an extremely easy to wear IEM that is very lightweight and small, and should fit comfortably with most ears.

Sound Impressions​

The TTROMSO is a V-shaped sound, with a big un-neutered bass boost and a equally big gain in the upper-midrange and low treble. It actually quite resembles my budget favorite CRA from CCA, which came out recently at only $14 USD. Imagine the TTROMSO as it's wiser sibling with a slightly more refined technical performance, but with all the same boombastic sound and occasional tingly sharpness.

TTROMSO's bass is dirty, and it's not clean, and it is really not that detailed, but it has punch and slam. The dynamics are decent, and probably on-par with the CCA CRA, and that's a good thing for a low price. Now, of course, this model is 6X more in cost, but still relatively inexpensive in the grand scheme of things. There's a big leap in overall bass quality when you move up in the 2x price range for sure.

The mid-range is mostly dominated by the upper-mids here, and on some tracks, I do find it a bit blaring and glaring, with a sharp and tiring attack. While the CRA had those moments occasionally, I do find the TTROMS to be a bit more fatiguing here.

That said, the overall mids and treble quality is a step up from the CRA, with slightly better detail, slightly better separation, and a little bit better exactness.

This IEM doesn't really blow its competition out and really kind of fits in-line with the rest of the under $100 price range. It's fun, and fits nicely, but I may consider spending my money on the CRA for a fun bass-heavy IEM and then using the rest of the money on a Moondrop Aria, and getting two solid IEMs with different styles for different music for around the same price as the TTROMS.


Headphoneus Supremus
Interesting Driver Config + Analog Sound
Pros: Warm, cozy analog sound
Swappable connectors (all included)
Open-back shell design
Above average soundstage and imaging
Very comfortable design
Cons: Mid-range lacks detail and resolution
Lacks isolation, if you care about that
Cable can get tangled easily

The RAPTGO Hook-X is an interesting new hybrid IEM that mixes two less common driver technologies together along with an even rarer open-back shell to create an exciting and somewhat refreshing new product on the market. The Hook-X retails for $239 and is sold by online retailer Linsoul. The product page can be found here:

As you suspect, this product was provided free of charge from Linsoul for review. And with that, let's talk more about this new in-ear monitor that's gaining some momentum in the community.

The Hook-X is a semi-open back design that has several perforations on the faceplate allowing sound to travel in and out. This isn't nearly as open as the Audeze iSine Planar series of IEMs, nor is it even close to an open-back headphone. It also still isolates more than ear buds, but it does let some sound go through and that's something I personally have been wanting a while just for my personal awareness around me, and the ability to relieve any pressure build-up and heat.

Inside this unique shell houses a 14.2mm planar magnetic driver and a "custom 18-layer double-side piezoelectric driver." With that said, I don't believe this is the same type of PZT ceramic driver that is found on previous IEMs which, in every case I've tried, have been piercingly bright and obnoxious to use. Nope, this is a different beast. In fact, the product box says its a bone conductor driver.

Bone conductor, you say? Like the Unique Melody MEST series? Like Aftershokz? Perhaps. It is also a known fact that bone conductor drivers are piezoelectric as well. So, I think that may end this confusion. And how does it sound? Well, that's the interesting part, and I'll talk about that after I discuss some cables and accessories.

Yes, as per usual, this product comes with a bunch of tips, and a fake-leather gray zip-up case. It's actually a decent case with a pocket inside and plenty of space to store things.

The cable included is green, just like the accents of the shell, and the cable connectors and also share green accent rings as well. The green braided cloth sheathing has a glowing green look to it, and it does look pretty neat. In actual use, it can become a tangled mess at times, but not too bad and not too annoying.

The connectors at the shell are flush-mounting 2-pins, and the opposite source end is a swappable cable feature. Included are a set of standard 3.5mm, and balanced 4.4mm and 2.5mm modular connectors. This specific modular connector-type is similar to the ones found on a lot of the newer chi-fi products coming out, such as from Kinera, Tripowin, and TRN. I am not 100% sure they are interchangable, but they all feature a push/pull insertion method with 4 pin connectors, and aren't held by a mechanical locking mechanism. Either way, it extends the length of the source connection by about 1/3rd of an inch and is not too distracting.

Sound Impressions​

So about that bone conduction thingy: My first impression putting these on and playing a variety of indie rock music was essentially, "wow, this is different." I couldn't totally put into words exactly what I was hearing. It sounded tonally balanced, and nothing really bad to say overall about its frequency response, which later measured just as well. But, there was just something unique about how it sounded in the mid-range, which coincidentally reminded me quite a bit of listening to your normal, average bone conducting earphone, such as the ones made by Aftershokz.

I happened to have a set with me just two weeks back, and had quite a bit of time listening to one of them, so I did have that interesting playback and presentation of music recently pushed into my mind. Literally? It's a different sound if you have never heard it before. It plays music, but it comes across more soft, more grainy in a way, and is not anything I would call high-definition, high resolution audiophile sound.

The Hook-X's initial impression has that type of mid-range to me. In my first pass through with, again, a lot of indie rock, vocal-led guitar music. I put down the IEM and wrote down my impressions online, as a record.

My first impressions of the Hook is that it actually has a mid-range that reminds me of the softness and lower-resness of Aftershokz, which I have listened to recently within the last couple weeks. That said, its a pleasant sound, maybe too smoothed over, and missing exacting detail and edge. It's tonality is for the most part fine, it just presents sound a little softer and different. I wouldn't call this hi-res audio for some reason, but this is just my initial impressions after about an hour of listening. These are very comfortable to wear and the color of the cable is really nice. Connectors are also swappable.

After coming back and listening several times with this IEM throughout the past week, my impressions went from medicore, to not bad, to somewhat enjoyable, to "wow, I just listened to these for 4 hours straight and it's way too late in the evening!"

What changed? Nothing really. Well, I did get a new DAP in-between listening sessions and going from the Hiby R5 Saber to the iBasso DX240 is a pretty big jump in quality. But, I did quite a bit of listening on the Chord Mojo/Poly as well, so I can't say it's just do to the step-up in source quality.

I think the Hook-X can take a little bit of getting used to to really enjoy its presentation style and uniqueness that is a little different than the other two recent planar IEMs on the market making a splash right now. In those, I mean the 7Hz Timeless and the LetShuoer S12, which I both enjoy and recommended in the past.

The Hook-X has a much more analog, cozy, and comforting sound to it that is different than the faster, edgier, and more in your face, high-definition-like sound of the other two planars. It does not necessarily put out the best hi-res quality, but it's still an enjoyable listen and beats other IEMs in a few areas, which made me spend hours and hours at night listening to this IEM.

What it does bring is a somewhat natural, analog, and somewhat lively sound that has good imaging and a good sense of space and openness. This could be partially attributed to the open-back nature of the shell, but the frequency response may also play a bit into this with a less forward upper-mid-range than other IEMs. I was surprised that I was able to overlook the grainy nature of the mid-range, which is pretty important to me, and just chill-out and relax to hours of various rock and jazz music and even listening to some old skool R&B jams.

The treble is extended and while it doesn't have the most air of IEMs, it still has plenty of output in these extreme areas to provide proper sounding percussions and reed instruments, all while not sounding muted and congested.

Final Thoughts​

The HOOK-X puts together an interesting package. It cost just a tad more than its competition, but is one of the rare semi-open in-ears on the market. It has an interesting sound signature that originally I disliked, and as I listened more, you can say that it "hooked" me in.

If you're looking for something that is clear, crisp, and forward, with the sound and presentation that is fast and hi-definition, this isn't the one you're looking for. If you want a more low-key, cozy and an analog-feeling sound that is easy on the ears and willing to sacrifice clean and clear mid-range, this isn't a bad choice at all. Normally these "analog" type sounds turn out to be horribly tuned (outside of say the Vision Ears and Sony gears), but this one is did a surprisingly good job of drawing me in over time and making me enjoy it as a nice alternative to my normal listening pattern.
Nice review. With all these planars coming up, I'm hopeful that someday soon we'd get timeless sq in a sub $100 planar.
No, I would prefer a new Timeless around the $400 mark. Imagine how good that would sound!!!
This is more my speed, I've had the LCD-2Cs for years and it's truly my end-game. I don't need anything else but then I got into IEMs recently and lets just say I'm quite happy with all the "planar war" going on because now I think I've found the perfect IEM alternative!


Headphoneus Supremus
Pros: Natural engaging sound
Has option of NOS and OS modes
Bitrates up to PCM1536 and DSD1024
High quality build
Cons: Lacks remote control
Interesting 3-legged design may bother some
Not the most layered/textured DAC around
Not as inciteful in attack as others (this is a preference thing)

The Pegasus is an R-2R Ladder Digital-to-Analog Converter (DAC) made by Chinese brand Musician. They are a new brand, which some have lumped with Denafrips, but Musician has their own expanding lineup of DACs, amplifiers, and streamers now. The Pegasus was their first product and one I purchased recently at their retail price of $1099 USD.

The Musician Pegasus uses a resistive ladder design instead of typical DAC chips that are found in many popular DACs out there that are normally using ICs from ESS, AKM, Cirrus-Logic, or Texas Instruments/Burr-Brown. This much more complex design requires matching many, many resistors and soldering each onto an intricate circuit board to create the conversion. Many of these DACs can be quite expensive, with some of the flagship products costing well over $10 to $20,000 USD.

In the case of the Pegasus, it is on the lower end of the R-2R market place as it stands today, though many may see that its still priced higher than many traditional DACs from Topping, SMSL, or the rest. The Pegasus does not cheap out on design choices or input/output.

The machined aluminum chassis is very well built and feels very premium with a unique 3-legged foot design and interesting bevels. The back of the unit has a variety of inputs and outputs. It'll output both single-ended RCA and balanced XLR, while taking in USB, Toslink Optical, Digital Coax, and the HDMI-based I2S. In both USB and I2S formats, the Musician Pegasus can take in sample rates of up to 1.536KHz, which is a whopping 32X sample rate, or two to four times more than most DACs on the market. It'll also transcode DSD format as well.

The high sample rate plus the "Non over-sampling", or "NOS", button makes a nice combination for users like me who rely on the third party up-sampling software, HQ Player, to do a lot of the DAC up-sampling, filtering and noise-shaping dirty work. In this case, I was able to up-sample to 32X without a hitch using Sinc-L filter, and I found the results quite pleasant.

On the hardware side, I really wished that Musician had included a remote control feature, and that all inputs were active when on. Each input is disabled when you change to a new input, and without the remote feature, it does require getting up and manually pressing the input button on the front of the device. Not a huge deal for some, but those who use this in a living room set-up or away from your seat of choice, it can be cumbersome if you use a variety of sources.

Sound Impressions​

At the time of purchase, I had been primarily using the Chord Qutest DAC in my main headphones listening station paired with the Bakoon AMP-13R headphone amplifier, and Hifiman Susvara headphones. I also have a Wyrd 4 Sound USB Recovery regenerator in-between the Roon Server PC and the DAC. I also use a variety of other gear such as the Sennheiser HD600 and HD800S, but the majority of my listening time comes with the Susvara.

I haven't had an R-2R DAC sitting in my home before, and the few times I've heard them were at meet-ups. I have owned the Schiit Bifrost 2 previously, which is also a multi-bit DAC, but uses a chip-based implementation and not an R-2R Ladder. I had heard about R-2R's warmer and more natural tuning, so I had some expectations coming in.

Surprisingly, I found the Pegasus to have a very neutral sound signature that had a slightly above neutral low end warmth and a sweet and smooth treble, though slightly rolled-off in NOS mode (without HQ Player) and less so on standard over-sampling mode. This was mostly in comparison with the Qutest, which I found to be very neutral, incisive, but not analytical.

If I were to really dig into the weeds, I'd say that the Qutest takes transients with a slightly edgier attack, while the Pegasus is more rounded, with a smoother finish. The Qutest excites with detail because of this, while the Pegasus still has all the detail but transitions gentler.

Without HQ Player, I did find the Qutest had a bit more depth, maybe an extra layer of detail. When I added HQ Player to my chain and upsampled to 1.536KHz to a NOS-enabled Pegasus, it really shined. The HQ Player's up-sampling, filtering, and noise shaping scheme added a noticeable rise in resolution, depth, and a slightly added mass to many of my tracks that really gave the Pegasus an even more natural and refined sound.

In my combination of headphones, amplifier, HQ Player/Roon settings, and DAC inputs, I decided to keep the Musician Pegasus in my system. It gave a different, but more natural and softer sound to my Susvara than the Qutest and I actually ended up appreciating that over the faster and edgier sound of the Qutest.

This review was a copied over from:
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Headphoneus Supremus
Pros: Stellar value at $220!
Best tuned planar IEM to date, and its not even close.
Good resolution and spatial qualities at this price point
Cons: Can be a tad bright at times, or with certain tips
Low end resolution is just average, and can be a little blunted.

Balanced tonality, crisp airy soundstage, rock-solid imaging, quick transients, punchy, slammy, and good dynamics with a decently wide soundstage. These combined terms don't typically come from me on most of the review units I receive, much less ones that are priced in the affordable range and by an obscure no-name Chinese brand like 7Hz. But, so it is.

I have never heard of 7Hz before, and Lillian from Linsoul asked if I wanted to try out this new planar magnetic driver in-ear monitor earphone called the "Timeless" several months back. As some may know, I enjoy my fair share of planar magnetic over-ear headphones, and have owned several disappointing in-ear planars in the past, and have demoed, reviewed and painfully listened to most of the ones on the market to date.

All of them are tuned terribly. Very few of them can be fully saved by EQ. The ones that do though can be technical beasts like the Audeze LCD-i4, but again, requires some sort of EQ capability on the go. Yes, Audeze packages their units with the optional Cipher cable, but that also requires a soon to be outdated lightning jack limited to iPhones and older iPads. Android users can get by with an Anker adapter but can't tune the Cipher since the App is iOS exclusive.

Enter the Timeless. It's all the things I mentioned in the first paragraph, and a shockingly good IEM at just $219 with a well thought out package to boot. Let's talk about it some more.


The Timeless comes in a simple box that feels a bit more weighty than one would normally expect out of an IEM package. The reason for this is because there a hefty machined aluminum hinged-flip-top box that is included to store and carry the Timeless in. It's a very nicely designed and finished case that should hold up to even big drops, while also feeling very luxurious and premium.

The Timeless also includes a series of tips and a silver-colored 2-core braided cable that I absolutely love. It's very lightweight, but feels and looks premium. Its the type of design choice I like and is similar to the same cables I bought from XINHS on Ali Express, except the Timeless cables have more premium connectors and splitters that are metal and color-matched to the black and red shell housing colorway.

The Timeless itself is a 14.2mm planar driver within the round disc-like aluminum shell. The driver size puts it smaller than my very own Unique Melody ME1, and the Audeze series of iSine/LCD-i4 and i3/Euclid, but however, it is larger than the RHA CL2, and the various Tin P1, P2, and other recent chi-fi planar iems.

At this size, it looks perhaps a bit intimidating; not as much as when I got the iSine and ME1 several years ago, but more so than other IEMs. But Timeless made this set very lightweight, and incredibly comfortable for my ears, which don't jibe well with certain IEMs. Surprisingly, I am able to wear this unit for several hours without any discomfort. I haven't had a chance to really see how long I could go, because I'm always interrupted by meetings or other things during the course of a typical day, but it's one of the few IEMs that I never feel when I'm wearing.

Sound Impressions​

Not feeling any discomfort is a good thing, because the Timeless sounds really good. It's rare that I have no urge to take off a random review sample that I never heard of before, after hours of listening for an entire week. There were times when I was grooving to jazz band, Go Go Penguin, or soul artist, Celeste, between meetings and begrudgingly had to take the Timeless off to attend to my calls.

Part of this was because the first time I put the Timeless on, I was immediately shocked that I heard a planar IEM that was tuned to be listenable without EQ straight out of the box. And not only that, but this was tuned better than MOST IEMs I've heard, no matter the driver configuration. It's just tonally balanced to my liking and if I had to describe it, I would say that it's perhaps a tad too elevated in the low end, but is very punchy and dynamic with a steady mid-range and an upper treble region that is right on the spot in terms of balance. The treble range is well-extended but can be just slightly north of neutral, but that also helps provide that dynamic sense and added excitement, while never sounding sibilant to me (YMMV, see more below). It's just a well-tuned device.

The Timeless's biggest weak point perhaps is that its not the most resolving planar out there. That belongs to the Audeze LCD-i4, which is priced 12 times more. But even so, it is still resolving, but maybe not enough for how much bass level it has. If I had to really nitpick, I'd say that the bass is just slight too much at times, and because it isn't the most resolving, or the fastest in transient speed here, that it comes off just a little blunted or lacking definition at times. To simplify it all, the bass range sounds more rounded than I would like and missing the final layers of depth and detail.

But that is nitpicking it down, because I find most everything about the Timeless to be very strong, and given its price, this is maybe a no brainer purchase for those looking for a "low-priced" IEM with high-priced sound. Wow, I am sounding very shilly in this piece, and that's not normally my style, but I have come away very impressed on this unit!

The other nitpick that I think some people may find with this is that the treble is a little spicy. I've heard that some do find it a little too bright, but for me, it's not a thing. I find its treble tuning to be smooth for the most part with good extension that really lets me hear those closing resonance of cymbals and hi-hats and strings of the jazz and bluegrass music I frequently listen to in my review playlists and my typical relaxing listening sessions.

If there was specific area where one may find this a bit on the harsh or aggressive side, I'd say that I found some brass instruments and saxophones to be a little more forward and more personal than maybe I want to on many jazz tracks I heard. I never found similar issues with female singers, though I've read about such things on the various forums. It could come down to tips, insertion, or general tolerance for treble sensitivity.


For just over $200, the Timeless is one of my new reference IEMs for this price range, maybe up to $500, as you start heading into Dunu SA6 territory. The Timeless really sets itself apart from the rest of the pack here with a good balance of tonality and technical performance where many of the attributes that make planar driver special seem to come off with this unit -- that is: quick speeds, solid resolution, separation and imaging. And even then, it can actually hit pretty hard with its elevated bass.

Add to that a nice carrying box, and a simple but attractive cable, and I think the Timeless really hits it out of the park. 7Hz, good job!

This iem can be purchased here:
Great review! Glad you mentioned that tips can change the perception of harshness. I've found from tip rolling that a treble peak in my Timeless could go anywhere from 5khz to 7khz or even disappear completely, depending on the tips I used. It boils down to insertion depth and the resultant ear canal resonance frequency. Hardly the fault of the IEM. So folks, you know what to do.


Headphoneus Supremus
Pros: Excellent tuning and technical performance
Great dynamics
Good soundstage and imaging
Premium accessories
Cons: Low-Mids are a tad leaner and drier than I would prefer
Shell is large and nozzle angle creates challenging fit for some

The Helios is a new in-ear monitor product from a relatively new brand out of Singapore called Symphonium. The brand started out in 2017 and have three current products in their line-up. The Helios is their flagship product and comes in at about $1099 USD.

The Helios features four balanced armature drivers in a configuration that was developed in collaboration with some familiar faces for those of you who have followed Audio Discourse on YouTube -- mainly Leneo, Toranku, and Valoncia, who have started their own brand, Subtonic, and working on exciting new products together.

So that's a heavy disclaimer here, as I have worked on Audio Discourse's YouTube channel along side some of the folks involved in the creation of this product. This tour unit was loaned out to me from Symphonium directly, and this unit, along with a few others across the world, are being sent to various people in the community for feedback and impressions. All that said, as usual, I try to minimize as much bias as possible and have come into this with excitement, but also will provide my critical takes as well.

The Helios tour unit was sent with two copper-colored balanced cables in 2.5mm and 4.4mm varieties. These two cables are very soft and supple, and I find them both attractive and easy to use. They terminate in 2-pin connectors, and unlike most cables available, these cables do not have pre-shaped hooks.

The package also comes with a hefty round screw-on metal case that is polished metal and has a nice attractive and luxurious look to it. I am typically not a big fan of these screw-on round cases, but this one is pretty nice and I'd probably use it for storage at home.

The Helios shell design is a rounded triangular shape that isn't too dissimilar from others like 64 Audio and Tachijim's general shape and design. It is however quite large, and has a deep cavity and a longer than average nozzle that is also about 5.75mm in diameter. It is a bit on the large side, and is meant to for a deep insertion into your ear canal.

This can present some challenges to small-ear hole folks like myself. My left ear was able to get a deeper insertion than my right, as my left ear canal is just slightly larger and has a less sharp bend to it. My right ear is narrow and has an early and sharper bend, and so the nozzle length and diameter hits up against my ear canal a bit prematurely, and so no matter how deep I try to push it in, its maxed out due to the interference.

This causes the IEM to stick out a little further and at a kind of strange angle out of my ear. All that said however, with the right sized tips (in my case, SpinFit CP100 Small), I was able to get a tight seal and no real issues with pain or discomfort. It just didn't look or feel as secure as I hoped it would. I did not have the same types of pain I felt with the Moondrop Blessing 2 or the Campfire Solaris despite them also having similar fitment issues due to nozzle length, width, and angle.

Sound Impressions​

The Helios is a very well-tuned IEM that expresses a nice deep sub-bass presentation with clean lower-mids, and a smooth mid-range and treble response that falls in-line with my preferences. It can be perhaps a smidge bright but nothing really to concern about if I had to nitpick its tonal balance. I could also ask for just a little more mid-bass for extra warmth and smoothness, but man, this is a nicely balanced IEM that should be a great all-arounder for most genres.

If I had not known the quantity of the driver count, I may have thought there were more. The 4-BA configuration gets a lot of performance on this IEM, especially when I compare it to my beloved 4-BA Viento B Custom IEM. Yes, that one is several years old now, but it still stands strong in my opinion due to its fantastic tonal balance and coherence.

The Helios takes a similar tonal balance, but adds more sub-bass performance and adds a lot more dynamics to the overall quality. Bass has better texture and punch, and there's a nice amount of sub rumble that can be felt in my ears. It can slam when it wants to, though not as much as some other IEMs I have tried of course. The Monarch and Odin slams just a bit more for similar sounding gear.

Symphonium's mid-range is a perhaps a tad lean in the lower end, but has a nice balance in the upper mids where I don't find it too lean nor too hazy. Some people may find this to be a tad lean overall given the entire mid-range response as whole, but for me personally, I really enjoy this presentation, which is slightly dry, but very clean and clear, and strikes a good equal balance to the spectrum.

Treble, despite being perhaps just slightly more elevated than I like, is very smooth. There is a refined and buttery slickness to it that reminds me of the best EST IEMs (i.e. Odin), or even the all-BA ultra-warm and laidback Vision Ears sets like VE8 and Erlkonig.

One of the most noticeable sonic impressions I found with the Helios, for good or for bad, is that it sounds like some notes or some frequency range sounds a bit more forward and closer to my ear than others. The midrange just seems a little bit louder than the rest, which is good for those who enjoy hearing the mids, and for some reason, I do feel like I am turning this IEM a little higher up on the dial than others. Still, I do find that I prefer a slightly more relaxed tuning, and at times I do think that the Helios' mids are a bit aggressive.

The dynamics are very well done. Despite what I say in the last paragraph, there are nice varying levels of sound range here, and quiet moments come off quiet while loud moments are intense. It's not the best IEM in terms of macrodynamics I've heard, but it's definitely above average.

I spent a lot of time with the Helios in all sorts of genres and musical selections -- anything from old classic rock, to jazz, to electropop and folk, to country and to classical. It does well with all genres. I did find it best for some music specifically though.

For example, the subbass gain, tacked on with the nicely tuned upper-midrange is a great combination for the newest Chvrches album, "Screen Violence." The Helios does well with the electropop band's mix of deep subbass synths, and Lauren Mayberry's vocals. Even the dark, emotive track "How Not to Drown" featuring The Cure's Robert Smith sounds fantastic on this IEM.

I also spent a bit of time listening to Massive Attack and Morcheeba, trip hop legends from the past with the Helios, and again felt it works well with this electronic brand of music. Helios provides the much needed deep subbass this genre asks for, while also the electronic synthesized keyboard play on full display.

I will say that my most listened to music of late, trio-based jazz music, is probably the least favorite stuff I have heard on the Helios. Perhaps it's due to the lack of low-end warmth and just not having the real grunt of the double bass stand out, or the slightly forward piano notes being a distraction. This wasn't my favorite combination for the music I played with on the Helios, but again, it is still very enjoyable and well-resolving for this music.

The Kilo-buck Market Competition​

The Helios enters competition against a lot of other $1000-ish in-ear monitors that are very popular and very good. Here are just some of the ones I can think of off the top of my head:

  • Campfire Andromeda (2020)
  • Sony IER-M9
  • Hidition Viento
  • Thieaudio Monarch
  • Unique Melody MEST

There are definitely others to consider, but these are some of my top ranked IEMs and are tough, tough competition for a new company with a new kilobuck entry. How does it stack up?

The Helios' defining difference between most of these IEMs is their sub-bass elevation and focus with the exception of the Thieaudio Monarch, which have very, very similar tonality. The Helios is more coherent, with better clarity and resolution from my memory versus the Monarch, and the treble is smoother. It's also a little more costly at $350 more.

The Andromeda is quite a bit different sounding, while also sharing an all-BA setup. Both have good dynamics and resolution, while the tuning is where they go off on different tangents. The Andromeda is warmer with a significant amount more lower mids and midbass compared to the Helios.

The IER-M9 is also an all-BA setup, and just has a much different sound. It's ultra smooth and warmly tuned and darker. Its a more relaxing listen and does not have a sub-bass focus. It's been a while since I really listened to the M9, but I never felt the technical performance as compelling on first glance as I did with the Helios. It's not saying that much, but perhaps it the smoother, warmer nature of the M9 not showcasing its full talents.

Finally, the two IEMs I do own: The MEST and the Viento...

The Viento is also a 4-BA setup, but I feel its tonally better than the Helios with similar upper mids and treble, but less subbass and more mid-bass warmth. It gives a more even sound throughout, while the Helios has probably a bit better clarity, texture, and excitement.

The MEST is quadbrid, that also has a subbass focus, but not nearly as energetic as the Helios. It also differs in the uppermids, where the MEST is quite a bit more relax and darker, given the comparison between the two very different flavors.

Podcast Impressions​

This was a live stream video of first impressions of the Helios from myself (Antdroid) and Rush on our Youtube channel:


The Symphonium Helios is a really nice entry to the market. I am quite impressed by its technical ability and it has a tonal balance that I think will make it a favorite amongst many, especially those who enjoy electronic and other sub-bass focused music. It has a lot of the tangibles in place to really set itself as the top "neutral with sub-bass" top dog in a crowded marketplace. While I still prefer my Viento-B, another "neutral with sub-bass" IEM just a little bit more for its tonal balance and warmth, I can see the Helios being a close runner-up, but with better technicalities.

The biggest gripe I really have with the Helios is the shell design. It's large, requires deep insertion, and I'd prefer a lighter acrylic shell over the metal housing it comes in, but for many, this might not be a big deal.

The Helios is good and a solid-buy. I look forward to the next Symphonium and Subtonic collaboration as I hear there's something(s) even bigger down the road in the high-end market that gets me very excited. This is a teaser, and a really good one at that.

Audio Discourse Interview with the Creators​

Finally, to wrap everything up, here's an interview with Subtonic hosted from Rush of Audio Discourse's YouTube channel.


Headphoneus Supremus
Pros: Warm, harsh-free tuning
Great cable/system
Good shell design
Cons: Perhaps a little too boring sounding
Not a fan of tuning nozzles in general (personal take)

The Falcon Pro is Dunu's latest ECLIPSE-based single dynamic driver in-ear monitor that uses trickle-down technology from the Zen and Zen Pro and their flagship Luna. This new IEM comes in at a relatively low price of $219 and is packed with goodies, which I'll talk about a little bit more below.

First off, I'd like to thank Tom of Dunu for providing me this review unit to try out and provide my impressions here.

The Falcon Pro is not only just a new IEM, but it also features the first use of Dunu's new modular cable connector system that I'm aware of. This new mmcx and silver-colored wounded and braided cable is very clean looking and easy to use. The new connector is a little bit easier to use as it is just pulled on without any moving mechanism to secure it into place. You do have to make sure you have it aligned correctly for it to fit. The new connector may look large in marketing images, but in reality, its actually a lot smaller than I thought and is a little more compact than the original Dunu modular connectors.

As with other Dunu products, there is a lot of tips provided, as well as a zipper carrying case. The case included with the Falcon Pro is a green canvas-like material and has a netted pocked on the inside. There's plenty of space for the IEM and tips and small accessories. My little Sony Walkman NW-A55 will actually fit inside this case as well!

Dunu uses a metallic shell that has a polished mirror look with 5 vent holes on the interior side. The shell design is tear-drop shaped and small to medium sized with a medium depth nozzle. My overall comfort level wearing these with SpinFit tips was excellent and I never felt like I needed to take these off nor had trouble with seal.

Sound Impressions​

The Dunu Falcon Pro exhibits a warm-bodied and smooth sound no matter the filter choice. Now, each one does something with the amount of bass and treble output, but overall the Falcon Pro has a warm and elevated bass response, and a slightly dark and relaxed treble range that makes it a comfortable listen for long periods of time. If anything, the Falcon Pro has a very vanilla, yet elegant sound.

For most of my listening, I decided upon the least bass, and more treble filter called the Transparency filter. This one provided a little bit less mid-bass, and just a tad more treble than the standard Reference filter, and the very interesting Atmospheric filter. With the Atmospheric one, it's hard to pinpoint exactly what is going on, as it doesn't necessarily sound as dark as it graphs, and provides an interesting level of depth and imaging that sounds a bit diffused out, and I don't tend to notice the dark FR response that it exhibits.

With the Transparency filter, I found the bass to have the least amount of bloat, though I wouldn't necessarily say that the other filters are excessively bloated. They have a very mid-bass focused sound but does not necessarily translate into a great amount of punch and slam. Instead, I find this to be a smooth and warm-bodied experience, with any of the filters. The Transparency filter, however, allows just a little bit more texture to shine, but at the end of the day, the Falcon Pro isn't the most resolving and texture-filled experience there is for an IEM nor does it compare to Dunu's higher-priced sibling, the Zen.

The Falcon Pro's midrange is even-keeled. It's warm and subtle and does not do anything to make it really stand out. Perhaps, this has to do with the elevated lower bass, and the Hifiman-like subdued 1KHz range, which gives the Falcon just a bit more space to play with in an otherwise warm-tuning that can cause music to come across just a bit more intimate than my normal preferences.

The treble response of the Falcon Pro shows a mature smoothness to it that isn't overly bright or sharp, but also not too dark either. It's got a decent amount of treble extension, but a softness to it that makes it sound very refined, especially at the price point it is targeting. Many IEMs in this price range don't really give the listener proper treble extension, and many mask treble extension-less with just peaks in the lower treble to give an overly sharp but "clarity" sound. In the case of the Falcon Pro, treble is present, but it does not stand out, which is nice. I wouldn't classify it as sweet totally, but it's nearing that type of sweetness that I desire.

The Falcon Pro's technical performance is a bit of a mixed bag. It's solid given its low price point, but I wouldn't consider it above average against other competition either. It has solid separation, and treble extension, but it lacks microdynamics and punch. It doesn't slam as hard as you may think given its FR graph, nor does it provide a great level of bass texture given its dynamic driver. But it does not falter in any of these cases either. It's just, average.

I gave out the sample units of the Dunu DK2001 and DK3001 Pro a couple years ago to the boys at and they still have them, otherwise I'd love to compare how these fare against one another. I think the Falcon Pro may go well head to head against these two, as a very similar cross of the two IEMs, with the bass/warmth of the DK2001 and the relaxed sound of the DK3001 Pro, but with more treble extension than both.

I did compare this to the smaller, but pricer Zen from Dunu. The Zen is punchier, more dynamic, and just an overall better IEM in many of the technical categories. The Falcon Pro does best the Zen in soundstage distance and treble extension though, and provides better instrument separation, but the Zen has better resolution, slam/punch, and a more exciting overall sound. I do like the Falcon Pro's tonal balance just a tad more just because the Zen can be a bit too forward in the upper mids, which can be fatiguing to me. That's never a problem with the more chillax Falcon Pro.


The Falcon Pro is a nice entry for Dunu. While I don't think it's something that is uniquely great or a world beater, I do think its a nice overall package when you consider the cable, accessories, and build quality. The tonal balance works well for many genres, and is smooth and warm and should work well for long listening sections. Plus, it has some treble extension!

Its not the most technical IEM on the market, nor even in its price class, but it sits in the average to above-average category of IEMs as a whole. That's not a bad thing, as it probably won't disappoint those spending their hard earned cash on this little package.


Headphoneus Supremus
Pros: Tuning is pretty solid
Cons: Shallow nozzle + small size makes it hard to securely wear
mediocre technical performance

The all-new P1 Plus is the latest in the P-series of planar in-ear monitors from Tin Hifi, and comes up against some very tough competition with the very good and recently released 7HZ Timeless. The P1 Plus was provided by Linsoul for review and retails for $159 USD, which is actually less than the previous P1 and P2 models.

Find the product here:

Visually, the P1 Plus looks just like the P1 and P2 models with a stainless steel mirrored-finish housing that has a rounded triangle shape. The unit continues to include a 10mm planar magnetic driver and uses MMCX connectors. The cable is a braided-copper color with metal connectors.

Sound Impressions​

Internally, I don't know if anything really changed, besides whatever was used for tuning. The P1 Plus is tuned differently, and is perhaps the best tuned IEM of all of Tin's product lines. I found the P1 Plus to have a laid-back and warm tuning, which has a dipped upper-mid range and treble, but with plenty of treble extension. The bass range is linear and extended, and not as elevated in the mid-bass as the other P-series IEMs.

When I first put the P1 Plus on, I felt it was pretty mediocre, in that it was tonally acceptable, but technically not. As with the other P-series, the fit was pretty challenging for me, and getting a proper seal and secured fit in my ears was difficult. I tried several tips, with varying degrees of success. Some caused extreme sibilance due to poor fit, and some just did not want to stay in when I moved. I ended up sticking with the included large foam tips that Tin supplies with this IEM.

With the foam tips, I was able to both get most of the sound issues out of the way, and I did not have any problems walking around and worrying about them falling out. With the foam tips, I'm sure it also helped with a some of the upper treble issues I was experiencing while using other tips, though not all of it went away.

One of my biggest issues with many of the Tin products is that they are brighter than my preferences. In the cases of their dynamic driver T-series, this was mostly in the upper-mids and lower-treble range being a little more exaggerated than I'd like to varying degrees, with the recent T2 Evo being the worst offender. In the P1 and P2, my troubles were set primarily in the upper treble.

For relatively budget IEMs, having upper treble output is not always a given, as many of them, at least until more recently, cut off sound at below 10KHz, making some upper-harmonic sounds very muted. High strings and cymbals sound more deadened than usual, so having upper-treble really makes these instruments sound alive, but too much can make them piercing and fatiguing. Such was the case with the P1 and P2.

These previous generation planar IEMs from Tin Hifi's biggest knock, tonally, was that they did not filter out these higher frequencies well enough, and in many of the music I listened to, caused quite a bit of ear pain. Sharp strings, extra splashy cymbals and hi-hats, and sibilant female vocals in poorly compressed pop music, amongst other audio artifacts.

With the P1 Plus, I found that the tonal balance was improved. The sibilance and upper harshness was reduced. It is still there, especially when I was using silicone tips and paired with my Sony NW-A55 digital audio player, but swapping to foam tips and using these alongside the Chord Mojo + Poly player, I found most of the harshness to disappear surprisingly.

The P1 Plus reduces the amount of mid-bass from the previous efforts with a more linear bass response that I prefer. There's no muddiness while listening to this set, and this along with the lower upper mid-range produces a warmer and thicker sound that still doesn't sound off. It's a richer experience than most Tin Hifi products with the reduced pinna compensation, but one that I find good for non-fatiguing listen. Of course, this is dependent on how much the upper treble bothers you.

Technical Musings and Comparisons​

On the more technical side, the P1 Plus isn't stand-out performer in this price-range. It shares many of the same things I found lacking in the P1 and P2, and when directly compared to the newly released Timeless planar IEM, it really shows its technical limitations. The Timeless costs a bit more, roughly $60 more, so budgets need to be taken into consideration of course, but I'll go over some of the areas where I find the P1 Plus and Timeless differ in technical performance.

I listened to a variety of jazz music from Go Go Penguin and Bill Laurence to Avishai Cohen and Joey Aleaxander, as well as the psychedelic guitar play of Tash Sultara, and soul music from Jorja Smith and Celeste during the music sessions between the two IEMs.

The main points that I came away with outside of just their tonal differences is that the Timeless has a larger presentation, more refinement, improved resolution, micro and macrodynamic abilities, and speed. In other words, it's a much more technical beast than the P1 Plus is.

The P1 Plus seemed to lack resolution, and in some cases quite a bit of it in some passages of Tash Sultara's latest album, "Terra Firma." Some of the small intricate guitar play just seemed like it was lost in the mix. In other areas, the P1 Plus seemed a bit sluggish in its transient speed and this probably contributes to the loss of refinement and resolution.

While the P1 Plus is warm and pleasing, it doesn't have the slam and rumble that the Timeless presents as well. The dynamics are also missing in general, as I found the P1 Plus's ability to clearly depict quiet and loud parts of some of my jazz tracks to be a bit lackluster. In general, most instruments and passages all sounded forward and close. There wasn't a large gradient or softness to parts of music that needed it. Instead, everything was a bit more in your face. I don't think this was as bad as the original P1, not even close, but it isn't the best I've heard at $159.


The P1 Plus isn't a bad IEM actually, despite its limitations. At $159, it is alright. It has a easy to listen to tonality, and for the most part sounds accurate. I found its technical ability to be just about average to perhaps slightly below at its price point, and that along with its kind of challenging fit, I don't necessarily recommend this for everyone. It's a decent IEM, and I won't fault someone for wanting it. I just find that there may be better ones around for the same, less, or slightly more money.


Headphoneus Supremus
Cayin C9: One of the Better Portable Tube Solutions for Portable Gear
Pros: Nice sound quality with no lack of treble air or low end grunt
Good Battery Life given the Amp configuration
Lots of Settings!
4.4mm Balanced Option
Nice build and feel
Cons: Gets pretty hot
Big and Heavy for pockets
Pricey ($2000)

For me, and for many entrenched in this audiophile world, there is always this fascination with analog tube amplifiers. It's old school, it's cool and unique looking, and it has its own set of parameters to mess around with. It also provides a different listening experience for the curious ear. I've gone through a number of tube amps in the past: from hybrids, OTL, or SET-style tube amps for headphones and speakers, and I've also gone through a few portable tube amplifiers as well. While I've had some success with the desktop ones, the portable ones have always been mostly misses or more of "what's the point?"

The Cayin C9 was announced a while ago and has more recently just showed up for sale. It caught my attention when it was first announced due to its looks and its specifications. It features both balanced and single-ended input and outputs, a nice sized volume knob, a switch to activate solid-state or vacuum tube circuitry, and an additional switch to active Class A or Class AB circuitry. In addition, this is a pure amplifier, and does not have a DAC, which lets users choose which pairing they want to go with it. Many portables are DAC/Amp combinations and does not give users the option to choose, which for most cases is the only way to keep them portable and have a small footprint.

The C9 comes in at a $2000 price tag, and is definitely on the upper-end of the portable amplifier market. It does, however, make up for its price tag with a very nice and high quality build, featuring an all-metal chassis that is simple yet elegant. The input/output connectors have gold rings around them, as well as the power button and volume knob to provide both style and functionality to its design.

The C9's tube selection is powered by Korg NuTubes. These are unique and a relatively new tube design that glow with green LEDs and are laid flat on the board. The Cayin C9 has two oval-shaped window cut-outs on the top surface of the amp that lets the Nutubes shine their alien look when activated. When off, the windows are very dark and internals are not visible.

The C9 is pretty hefty, and definitely not pocketable. It may fit into a large coat pocket, but the weight would be pretty distracting and heavy to carry. Instead, this is definitely made for bag travel, and to sit on a solid table surface when in use. Due to the amp selections and metal chassis, the C9 also gets very hot in any of the combinations, and you'll probably want to minimize contact with it when it has been running for a short time. It will heat up the area around it.

Note: The Cayin C9 amplifier was provided on loan as part of a private review tour hosted by Cayin directly. I will be shipping the C9 amplifier to the next leg of the tour in Europe immediately after this review.

Sound Impressions​

The Cayin C9 has two "timbre" modes (solid-state and vacuum tube) and two amp circuits (Class A and Class AB), giving it a total of 4 combinations of user amp configurations. There is, of course, a high and low gain setting, but I'll just say that for headphones, I used high gain, and for IEMs, I used low gain for all my impressions.

I'll first take a look at some of the basic power demands and general observations and then go into the different configuration impressions and finally comparisons with other portables I have on hand.

Initial Stress Test​

When I first took out the C9 and got it setup, I connected my Lotoo PAW 6000 digital audio player with line-out enabled into the input of the C9. I used balanced 4.4mm interconnects, which are provided with the C9 and are quite stunning looking. The C9 also includes matching 3.5mm to 3.5mm interconnects as well.

My first stress test was to see how the notoriously hard-to-drive Hifiman Susvara planar magnetic headphone would sound with the Cayin C9, however only using the 3.5mm singled-ended output which has less power capability. I enabled Line Out on the PAW 6000 and set the switches to High Gain, Class A and Tube mode on the C9 and it was time to rock n' roll. I put on Grace Potter & The Nocturnal's modern classic rocker, "The Lion The Beast The Beat" and was happy audio came out, but I wasn't thrilled that I ran to the end of the line on the volume knob.

Now mind you, it got loud enough for me to enjoy music at almost my normal listening volumes (roughly 70-75dB SPL@ 1KHz), however for some, that may not be loud enough, and this specific headphone pairing didn't get it to even that level. Unfortunately with this, I did find the C9 to sound a tad bright, thin, and just lacking a great mid-range and smooth treble that I'd expect from the Susvara. The low-end held up fine though, surprisingly.

But, let me reiterate, this was just a stress test, and very, very few headphones require the amount of sheer power that a Susvara does and I also only tested it out of the weaker single-ended output stage. The majority of headphones and earphones I tried worked well within the bounds of the C9's power output.

Headphones Pairing with the Sennheiser HD600​

Now with that out of the way, I spent the majority of my headphone experience with the Sennheiser HD600. This is a classic reference headphone that many in this hobby have heard, and has a very well known and established tonality and timbre that appeases most people. It also pairs extremely well with most tube amplifiers, and so this was one that I had some good expectations for.

On this pairing, I kept the PAW 6000 in the chain, turned it to NOS mode, connected it as a DAC to my computer and turned on Roon and HQPlayer. I set HQPlayer to 768kHz oversampling with the Sinc-L filter and fired off some music.

First, I compared Class A and AB using the Tube mode on high gain.

In "Restless" by Alison Kraus & Union Station, I found the angelic voice of Kraus to sound really no different between either of the Class modes. In Class A mode, however, I did find the low end bass guitar to have just a slight amount of more impact, while the Class AB mode had a softer and brighter midrange.

Switching over to the live recording of Bill Laurence's "The Good Things" from "Live at Ronnie Scott's", I found there were some more noticeable differences between the settings. The Class A setting had a more warm sound but with a more muted piano strike, especially around 0:54 in the track. In Class AB mode, this piano attack was slightly more strained with more resonance in comparison.

I continued to listen and moved quickly towards the mid-point of this track, where the stand-up bass solo begins around 5:38 into the track towards the end. In this case, the amp settings did not seem to make any pronounced differences.

So, of course, I decided to mess around with the "timbre" switch. I flipped back and forth between Solid-State and Tube modes and found that the second half of the track, which is led by a bass solo, while drums and keyboard are still continuing in the background, had some more appreciable differences.

In Solid-State mode, I heard harder transients with more crisp edges, while also have more defined cuts. While in Tube mode, the transients became softer and sustain notes held longer with more decay and just an overall more euphonic sound.

At this point, I wanted to try some older music, and pulled out some classic Beatles music. On "Let it Be", Paul McCartney's vocals sounded much the same between any of the settings I messed with, but the most audible change between modes was how drums sounded. On Solid-State mode, drums sounded a tad thin and lean, and lacking the heft and weight I heard while on the Tube mode, which sounded more realistic and defined. I also felt the whizzing guitars and bass around the 3 minute mark sounded clearly better with the tube amp enabled.

There are many great Beatles tracks, but one of the more memorable introductions is the combination of drums, bass and buzzing guitars of George Harrison's "While My Guitar Weeps". In tube amp mode, this intro has a softer guitar presentation, and a smoother transition from the initial introduction to the guitar frenzy later. In Solid-State mode, the imaging is improved and things are little more separated, however, guitars are sharper but also more defined.

Some Time with In-Ear Monitors​

I also spent a bit of time with various in-ear monitors on the low setting with the Cayin C9. No matter which IEM I used, I did not find any issues with hissing or noise. All of them had black backgrounds, and no trouble with any sound anomalies. For reference, I used custom Hidition Viento and Unique Melody MEST, and also some time with the universal Shuoer EJ07M, Dunu SA6, and Kiwi Ears Orchestra.

I spent most of the time here with my two customs. With the Viento, I thought the pairing was alright. The Viento is a very neutral reference monitor, with a small bass boost. The Cayin C9 tube amp had a clean signature, that had just a slight amount of warmth, but a surprising amount of air and treble quantity to it that I wasn't expecting. It never felt harsh though with any of the IEMs, and that was good. It felt relatively sweet, especially after the initial brightness I found with the Susvara. Luckily, this isn't the case here nor was it with the HD600.

I thought the pairing with the Unique Melody MEST was quite nice. The MEST is a quad-driver IEM with dynamic driver, balanced armatures, electrostatic-tweeters and a bone conduction driver. The MEST's relaxed, yet exciting signature had some extra pop and reverbish sound to the low end while using the C9 in Tube, AB mode. Those Bill Laurence Trio live tracks had a nice amount of energy and an organic decay that felt very nice physically and mentally.

All in all, I think the C9 plays well with IEMs, which I will say, isn't a typical thing with many portable tube amplifiers. Many are just too loud for most IEMs or have loud feedback from amp noise or electromagnetic interference (EMI) from phones or other wireless signals. The C9 is quiet. Very quiet.

Comparisons with...​

Lotoo PAW 6000​

The Lotoo PAW 6000 is my current audio player of choice when it comes to portability since it has a lightning fast UI, easy touch interface, and a really nice sound signature that is resolving yet natural without sounding too stuffy or too bright. The sweet treble is probably my favorite part of the experience.

I spent a good chunk of time using it as a DAC for the Cayin C9 and then quickly A-B switching between the player directly and the amplifier. This worked well since I was able to use balanced cables for the I/O between the two devices and 3.5mm cable for headphone listening.

The PAW 6000 surprisingly sounded a touch warmer than the C9, with just a little bit more elevation in the lower midrange and a more relaxed treble range. As mentioned previously, I don't think the C9 is utterly bright, but I did notice it sounds like it has a little more energy up top than the other amps I have been using and own today. The C9 is also a little more precise in some ways, especially in solid-state mode. In tube mode, I do find these two line-up more comparably.

Chord Mojo + Poly​

The Chord Mojo + Poly combination is new to me. I only just received it a couple days after I got this C9 and intend to use it as a portable Roon streamer while in and around my home. In my brief time with both of these amps, I have noticed the Mojo plays just a bit more warm, a little more rounded in the edges, and a little more contained. The C9 has a little more pop and dynamic energy, and again, has a more lift in the upper range.

Both of these have equivalent power, though, I think the Susvara had a little more drive with the Mojo than it did with the C9. Again, this is a crazy ask for either of these amps so take that with a grain of salt. In other headphones play, I found power to not be an issue on either of these units.


Ignoring the price tag, the Cayin C9 is a very nice addition and one of the better portable tube amplifiers on the market. It has a nice high quality build, pretty Korg NuTubes, and solid feeling switches and knob. The battery life also seems pretty good in my experience especially given how much heat this thing generates and the amp circuitry.

If I had to criticize anything, it would be that its a bit large, and heavy, and not super easily transportable without a bag. It also has a hefty price tag at $2000 USD, and puts it in the upper echelon of portable amplifiers.

But that said, I do like what I heard. It does not necessarily present the stereotypical warm and liquid sound that many think of tube amplifiers, but instead softens the transients just enough while keeping the upper range active and energetic to keep dynamics alive and resolution in-tact. It definitely outperforms other portable tube amplifiers I've tried, albeit, those were significantly less costly. So in the end, its a big dollar amplifier for those who can afford it. Its worth a demo for sure.