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Multi-Portable Amp Thread: 16 amps reviewed (Leckerton UHA-6S MKII added)

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Thread Starter 

Multi-Portable Amp Thread

 

Amps mean different things to different people.  It depends on your use, music,  source, headphone, and ears to determine if an amp will make a difference, and if so how much.  As primarily an IEM guy, I have had mixed results with amps through the years depending on the factors I mentioned, and while this review thread can’t possibly cover all the iterations of product combinations, it will compare the general performance of each amp.  I do have more specific amp matching with headphones/sources in my custom IEM reviews.  My Google+ page.

 

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click images for full sized picture

 

Portable amps reviewed:

-          Headphonia Arrow 12 HE

-          Headamp Pico Slim

-          Meier Audio Stepdance (original)

-          Neco Soundlab DUAL AMP portable headphone amplifier – V2

-          iQube V2 (with DAC)

-          Auzentech i.Fuzen HP-1

-          Furutech Cruise (with DAC)

-          Just Audio uHA-120

-          Portaphile 627

-          Epiphany Acoustics EHP-O2

-          Headphonia Arrow 12HE 4G

-          Shonyun 306

-          JDS Labs ODAC, O2, and ODAC + O2 combo (simulated)

-          Additional amps reviewed in the 2nd post due to the slow response of this post.

-         Pre-review impressions can be found here.

 

 

But, before reading further, here are my notes from testing:

- I primarily review and listen to custom IEMs and some, such as the JH16, LS8, and Infinity X3 are not dependent on the quality of the amp and there are small to minimal differences between the amps to my ears.

- These amps are fairly close in sound signatures and the differences between the amps is not as large as the difference between headphones/IEMs.

- The differences between the amps in frequency response is very minimal.

- A good amp can improve the sound of lower end headphones, but a good headphone from the headphone out of a relatively low end source (Clip+ or iPhone) can sound better.  Which is better overall depends on the combo and what you want.  I have heard what I consider huge improvements from some combinations such as the Ortofon e-Q7 and the ALO Rx amp or a MEElectronics CC51 and the Meier Audio Stepdance.

- With lower end DACs the differences between amp performance is less than with higher end DACs such as the Anedio D1 and HiFiMan 801, as would be expect.

- Using an amp from the headphone out of a player has marginal improvements for either output impedance mismatch reasons, or internal PMP amp limitations.  For example an iPod/iPhone/Fuze sound better to me from a line out than when amping the headphone out.

 

Important notes about the charts and ratings: The relative differences between the rating numbers are not all that large.  For example a score of an 8 in the bass isn't an overwhelming difference, but is very apparent in comparison with something rated at a 5.  While I didn't list synergy with various headphones, some react differently with certain headphones, however the relative sound and technical ability is usually remains the about the same comparatively. 

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Manufacturer: Headfonia
Model: Arrow 12 HE

Price: $249
Product notes: discontinued, replaced by the 3G and soon to be replaced by the G4
Type: portable amp
Volume control: analog, wheel
Power connector: USB (mini B)
Features:
- gain switch (0, I, II)
- bass switch (0, I, II) - 0db, 6 dB, 12 dB
- crossfeed (0, I, II)
- impedance switch (0, I, II)  10 ohm, 70 ohm, 120 ohm
- auto power off mode (3 switch positions: on/off/auto - auto turns the amp off after 60 seconds of no input signal)
- two input locations   
- slim design
Works with 4 pin headphone plugs: Yes
Sound signature: A spacious and warm presentation that generally adds width to the presentation while not necessarily adding to the depth.  The low through mid-bass is slightly elevated but the sub-bass is not.  Due to the bass presentation and spaciousness, the midrange seems slightly more laid back and the treble is more neutral/laid back.
Sound quality: The quality of the Arrow 12 HE varies greatly depending on the IEM and headphone due to the high output impedance as with many custom IEMs that have crossovers the sound is on the flatter side while others such as the TS842 (and ER4P) improves quite a bit with the impedance switch turned on, adding smoothness to an edgy and analytical presentation.  Overall, the resolution is a step below others such as the Pico Slim and Stepdance, but not always.  Driving full sized cans, the Arrow 12 HE does an acceptable job but the slim portable design does show limitations in dynamics compared with something more powerful such as the iQube, Stepdance, or Neco.  When paired with dynamic driver IEMs the sound is overall good and other than deep bass roll off for lower impedance headphones/IEMs, there is no effect of the output impedance.
Channel Imbalance: Yes, at very low volumes only with high sensitivity IEMs
Hiss: There is no appreciable hiss with the JH16 on low gain at max volume or below.
Interference: Slight clicking with the iPhone 3G when the phone is connecting to the internet.  No interference with the Blackberry Bold.
Summary: The Arrow 12 HE was a great amp when it was released due to the combination of size, shape, performance, and features as well as the amazing driving ability due to the three gain settings.  Still OK by today's standards, there have been other amps that have surpassed the performance of the Arrow 12 HE including the prototype G4 that I had a chance to audition.  The Arrow 12 HE really is dependent on specific matches with balanced armature IEMs as the output resistor either helps, hurts, or doesn't affect the sound, but you won't know unless you either try or read about it from others.  Dynamic driver armatures do respond well however as do lower end headphones.

 

Preview: I had the opportunity to try a G4 prototype board and the improvement was anywhere from a decent amount to substantial depending on the headphones used.  The G4 has more resolution and is closer to the performance of the Pico Slim and Stepdance and I am looking forward to hearing the G4 when it is ready.

 

 

Manufacturer Model Price Form Factor DAC Power Charge
Bit Depth Sample Rate
Headstage Arrow 12 HE $249 Flat N/A N/A Battery USB

 

 

Quantity Warmth Note Sustainment Smoothness Soundstage
Deep Bass Bass Mid-Bass Midrange Upper Mids Treble Width Depth Imaging
3 5 7 5 5 4 7 6 6 8 4 4

 

 

Bass Mids Treble Transparency Dynamics Resolution/ Detail Clarity Soundstage Score Total - Quality Hiss Imbalance Total Quality, High sensitivity IEMs
Quality Quality Quality
4 5 5 5 5 7 8 5.3 5.6 10.0 9.0 8.2

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Manufacturer: Headamp
Model: Pico Slim

Price: $399
Product notes: The Pico Slim is the smallest high performance amp I know of and the size and shape make it perfect for on the go use with a minimal size addition to your source for powering IEMs and easy to drive portable cans.
Type: portable amp
Volume control: digital, knob
Power connector: USB (Micro B)

Battery life:
Features:
- Tiny size

- On/off switch which allows you to leave the volume where you want it between listening sessions
Works with 4 pin headphone plugs: Yes

Sound signature: The Pico Slim has a very transparent and fairly neutral sound that is on the brighter side of the spectrum.  It does not lack deep bass oomph, but the deep bass isn’t quite as accentuated and powerful as other amps such as the Stepdance or Cruise resulting in a slightly thinner sound.  Overall the Pico Slim doesn’t add much coloration to the sound and offers very good transparency.  The soundstage is on the average side but does offer very good depth and proportion to the sound resulting in a realistic yet somewhat intimate sound.
Sound quality: With exceptional transparency and very high levels of resolution, the Pico Slim performs very well technically.  The biggest issue I had with the Pico Slim with BA IEMs is that the notes can become slightly thinner than usual, and with some already thinner sounding BA IEMs this is not my ideal sound.  However, overall the results are exceptional.  With dynamic driver IEMs the Pico Slim performs quite well, however it doesn't have the bass control of some of the larger amps such as the Stepdance, iQube, and Cruise.  The Pico Slim isn't great at driving harder to drive headphones except for fairly low volume listening, and then it is on par with the Arrow 12 HE; good but not great.
Channel Imbalance: No

Hiss: Turning the volume knob up past the halfway point with the JH16 results in audible hiss, however when music is playing that volume level is louder than I would listen.  The hiss could be an issue with a low volume source, but I have not come across one that has caused an issue.
Interference: No interference from both my Blackberry Bold and iPhone 3G
Summary: For the size and shape the Pico Slim is a great little amp.  It offers exceptional transparency and plays well with custom IEMs, including high sensitivity ones, as well as dynamic driver IEMs.  Both the Arrow and Pico Slim are very easy to carry around with my modded iPod and the Pico Slim gives me consistently great sound, although in direct comparison the thinner and brighter sound if the Pico Slim doesn't always match well with brighter and thinner sounding IEMs.  With absolutely no imbalance, no interference, and no hiss in my experience the Pico Slim is an excellent choice for high sensitivity custom IEMs. 

 

 

Manufacturer Model Price Form Factor DAC Power Charge
Bit Depth Sample Rate
Headamp Pico Slim $399 Mini N/A N/A Battery USB

 

 

Quantity Warmth Note Sustainment Smoothness Soundstage
Deep Bass Bass Mid-Bass Midrange Upper Mids Treble Width Depth Imaging
4 4 4 5 6 7 4 5 5 4 5 5

 

 

Bass Mids Treble Transparency Dynamics Resolution/ Detail Clarity Soundstage Score Total - Quality Hiss Imbalance Total Quality, High sensitivity IEMs
Quality Quality Quality
8 9 9 10 5 9 7 4.7 7.4 10.0 10.0 9.1

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Manufacturer: Meier Audio
Model: Stepdance

Price: $349
Product notes: Discontinued; replaced by the 2stepdance.  I have owned the Stepdance for a while and have noticed it is a great performer with a wide range of headphones and IEMs rarely having a poor match.
Type: portable amp
Volume control: digital, knob
Power connector: Non-standard, for power only; unit does not charge battery

Battery life: Up to 8 hours with 600 uHa rechargable in low gain, high current mode, but typically closer to 6
Features:
- Active ground that simulates balanced in a single ended design

- Low and high gain switches

- Low and high current switches
Works with 4 pin headphone plugs: Yes

Sound Signature: The sound is on the warm side, but not all that warm, however the deep bass region does have some extra kick to it to go with the superb control.  The midrange disappears and is neutral while the upper mids and treble are slightly on the brighter side of neutral.  The width of the space scales with better DACs a bit better than average amp I reviewed while the depth and imaging are average.

Sound Quality:  Bass control is the first thing that comes to mind when I think about the Stepdance, but it has so much more to offer.  I was actually surprised by where the amp rated overall in my scoring system as it really doesn't do anything wrong. Resolution is very good with a slight liquidity to the presentation and better than average smoothness leading to a fairly transparent sound.  The Stepdance can drive harder to drive cans quite well and to loud volumes, performing in the top half.

Channel Imbalance: No

Hiss: Hiss is dependent on the volume setting and turning up the volume will result in more hiss.  I hear no hiss at normal listening volumes with any headphone/IEM I tried.
Interference: None.
Summary: The Stepdance has impressive sonic performance for the size and price with the ability to drive just about anything.  The bass is one of the best I have heard in a portable amp with a combination of control, depth, and punch.  This is the only portable amp that requires an external battery charger, but it can accept other external batteries of up to 15V if you choose to carry one.  With an overall great performance the Stepdance would be a recommended amp, but now that the 2stepdance is out and uses different op amps I am not 100% sure how that amp performs.

 

 

Manufacturer Model Price Form Factor DAC Power Charge
Bit Depth Sample Rate
Meier Audio Stepdance $349 Portable N/A N/A 9V or wall N/A

 

 

Quantity Warmth Note Sustainment Smoothness Soundstage
Deep Bass Bass Mid-Bass Midrange Upper Mids Treble Width Depth Imaging
7 6 6 5 5 5 6 6 8 7 5 5

 

 

Bass Mids Treble Transparency Dynamics

Resolution/

Detail

Clarity Soundstage Score Total - Quality Hiss Imbalance Total Quality, High sensitivity IEMs
Quality Quality Quality
9 9 8 8 8 9 8 5.7 8.1 7.0 10.0 8.4

 

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Manufacturer: Neco Soundlab
Model: DUAL AMP portable headphone amplifier – V2

Price: $161 ($117 + $23 for AD8610 opamp + $21 for 600 mAH li-ion battery)
Product notes: Neco, the amp designer, is a great guy and will be happy to work with you on your custom needs fot the amp.  Thank you Neco!  This is the lowest cost amp in this review, therefore it stands alone.  I have owned a few amps in the same price range, but none have preformed to the level of my Arrow, yet the V2 does. 
Type: portable amp
Volume control: analog, knob, logarithmic
Power connector: Custom connector

Battery life: 24 hours at low volumes
Features:
- On/off switch which allows you to leave the volume where you want it between listening sessions.

- Logarithmic volume control for less low volume channel imbalance
Works with 4 pin headphone plugs: Yes

Sound signature: The V2 is a fairly neutral across the spectrum with an ever so slight bump in the midrange.  If it weren't for the slight bump in the mids, the V2 would be flat. 
Sound quality: For the price the V2 performs quite well.  While it isn't the best performer, it holds its own and is slightly better than the amp section of the D10 and does best some others in certain categories.  It has very good dynamics while the soundstage and imaging are average.  The V2 performed about average pushing the LCD-2, which is impressive for the price.

Channel Imbalance: Yes, at low volumes with very high sensitivity custom IEMs such as the JH16.  I initially received the amp with a standard volume control and the imbalance was much greater.  Let Neco know what you want and he will make an amp specifically for you, including a lower gain if you want to use the amp with high sensitivity custom IEMs.

Hiss: Hiss is dependent on the volume setting and turning up the volume will result in more hiss.  I hear no hiss at normal listening volumes with any headphone/IEM I tried.
Interference: None
Summary: With the form factor similar to the Stepdance, an internal 9V battery with an internal charger and better battery life the V2 is a great performer for the price.  If you use high sensitivity IEMs make sure to get the logarithmic volume and have Neco set the gain lower (mine is standard gain).  For dynamic driver IEMs or headphone this shouldn't be an issue.  While the V2 isn't quite a giant killer, it is a giant in its price range. 

 

 

Manufacturer Model Price Form Factor DAC Power Charge
Bit Depth Sample Rate
Neco Soundlabs V2 $161 Portable N/A N/A 9V Wall

 

 

Quantity Warmth Note Sustainment Smoothness Soundstage
Deep Bass Bass Mid-Bass Midrange Upper Mids Treble Width Depth Imaging
6 5 5 6 5.5 5 5 5 5 5 5

5

 

 

Bass Mids Treble Transparency Dynamics Resolution/ Detail Clarity Soundstage Score Total - Quality Hiss Imbalance Total Quality, High sensitivity IEMs
Quality Quality Quality
8 8 7 6 7 8 8 5.0 6.9 8.0 9.0 8.0

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Manufacturer: Quables
Model: iQube V2

Price: $699
Product notes: Class D amplifier
Type: Portable DAC/amp
Volume control: Analog, knob
Power connector: USB (mini B)

Battery life: (4 AAA batteries) Unfortunately I didn't have the opportunity to run the iQube until the batteries ran out, but I did use it for several hours for over more than a week before the battery needed a recharge driving IEMs.  Per the manufacturer the iQube V2 should last between 10 and 20 hours depending on the headphone/volume used, however I think I got more time out if the iQube than 20 hours.
Features/Information:
- 16 bit, 32 / 44.1 / 48K sample rates

- CS4344, 24 bit delta sigma DAC

- Gain switch (low gain = 2, high gain = 7)
Works with 4 pin headphone plugs: Yes

Sound signatureThe iQube V2 is neutral through the midrange and treble with an emphasis in the bass region resulting in a warmer presentation.  Recreating a spacious and 3D soundstage, the transparency is very good letting the rest of the chain impart the sonic signature on the presentation more so than the iQube, which is what you want in your amp!  The DAC section is also very transparent and doesn't change the sound signature of the iQube.

Sound qualityThe overall quality of the iQube was very good with just about everything I threw at it from the K701 to all of my custom IEMs to various dynamic driver IEMs/ear buds I have lying around.  There is no lack of power in the bass region, but with the bit of enhancement the iQube sounded a little less controlled in comparison with amps such as the Stepdance and Cruise.  Dynamics are good and near the top of the performance curve, but not the best both as an amp and as a DAC.  Resolution and clarity were also very good, but not at the top of the performance curve. 

 

Paired with my high sensitivity custom IEMs, lead by the JH16 and LS8, the iQube did a good job but there is hiss and a slight channel imbalance at lower volumes.  Pairing is dependent on the sound signature of the custom IEM, but in general there were no bad matches and the iQube was at or near the top of the performance heap.

 

When coupled with the LCD-2 v1 the iQube did a good job, but not great, however no portable amp compared with the Anedio D1 desktop DAC/amp.  The K701 sounded spacious and had plenty of bass with good control, resulting in a musical combination the combines the strengths of both the amp and the headphone.  Combining the what the iQube does well it performs quite well overall as both an amp and a DAC.

 

Note: After my listening I read other reviews of the iQube V2 and for some reason I seem to hear the V2 differently than other reviewers as the bass was more emphasized and in comparison with the other amps in this review, specifically the Stepdance, D10, Cruise, uHA-120, and Pico Slim, the iQube sounded on the warmer side of neutral and didn't have quite the bass speed or control.  The differences were smaller with lower resolution headphones, but still there to an extent.  

 

Channel Imbalance: Yes, with the JH16 at low volume levels, but not an issue with the majority of my custom IEMs and not an issue with headphones.

Hiss: There is slight hiss with the JH16, and the hiss is constant and does not change with the volume.
Interference: Setting my Blackberry on the amp or within about 8 inches resulted in some noise.  My iPhone 3G did have interference when connecting via wi-fi, but that was reduce a good deal when I switched to 3G service.  The iPhone didn't interfere with the amp when it was 1.5" or further away.
Summary: The iQube is a very nice amp that does many things right and nothing really wrong.  The combination of amp and DAC come with a space premium resulting in a portable amp that isn't all that portable, or at least pocketable.  But if you do want to bring it along with you the results will be great sound from either a computer or another source.  The amp section is very good but not the top performer despite the highest price, although not technically that far off.  The DAC section is high quality and does not alter the performance of the amp vs. when used via line-in from higher performing DACs such as the 801 or D1, although the DAC doesn't have the resolution of those two, but depending on the headphone used, track, and bit depth, the DAC differences are not very large. 

 

Taking into account the overall performance of the iQube vs. the competition, it is a very strong performer.

 

 

Manufacturer Model Price Form Factor DAC Power Charge
Bit Depth Sample Rate
iQube V2 $699 Portable 16   Battery USB

 

Quantity Warmth Note Sustainment Smoothness Soundstage
Deep Bass Bass Mid-Bass Midrange Upper Mids Treble Width Depth Imaging
3 5 7 5 5 4 7 6 6 8 4 4

 

 

Bass Mids Treble Transparency Dynamics Resolution/Detail Clarity Soundstage Score Total - Quality Hiss Imbalance Total Quality, High sensitivity IEMs
Quality Quality Quality
8 9 9 9 7 9 8 5.3 7.8 9.0 9.0 8.6

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Auzentech i.Fuzen HP-1 iPhone 4/4S amp case

 

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Manufacturer: Auzentech
 

Model: i.Fuzen HP-1
 

Price: $129
 

Product notes: iPhone 4 & 4S case amp with built in battery
 

Type: iPhone 4/4S case amp
 

Volume control: digital, touch buttons
 

Power connector: USB (mini B)

 

Battery life: Using the battery for the amp, the i.Fuzen easily outlasts the iPhone.  If used as a backup battery the i.Fuzen was able to maintain the iPhone charge and play for at least 8 hours while still having 2 to 3 bars of power left, depending on how much data/voice was used. 
 

Features:
- Low and high gain 3.5mm output jacks

- Can be used as a battery for the iPhone
 

Works with 4 pin headphone plugs: Yes

 

Sound signature: More laid back than the iPhone 4S headphone out with a more spacious presentation that doesn’t lose the presentation depth.  Due to the more spacious sound, the imaging and apparent detail levels are higher.
 

Sound quality: Depending on the headphone used, the technical improvements vs. the iPhone 4S range from small to significant.  The 4S sounds good, but lacks resolution and doesn’t control the drivers all that well when there is lots of bass.  While the i.Fuzen has a higher resolution with the 4S, the difference isn’t all that large, but what does improve is the control and clarity of the presentation.  It is due to the improved control, larger space, and laid back in comparison presentation making the details stand out more with better articulation.   It is difficult to compare with my other portable amps due to the form factor except with an iPhone, but the i.Fuzen keeps up with more expensive amps.  One potential issue is the digital volume steps with ultra sensitive custom IEMs as the JH16 on the lowest volume setting was quite, but not as quite as I would listen to if I wanted to fall asleep with the JH16.  But that is not a big issue for on the go since there is usually always background noise.

 

I used the high gain headphone jack (the one with two dots) with the K701 with very good results.  First, the K701 sounds very bass light from the headphone out while the i.Fuzen adds a good amount of body and depth to the bass.  Dynamics and depth of the presentation are improved resulting in a more natural and open sound.  During my testing I was distracted and after a bit I was thinking the sound was pretty disappointing and I noticed I was connected to the iPhone HPO and when I switched to the i.Fuzen I immediately noticed the quality improvement.  The i.Fuzen can drive the 701 much much louder than the HPO from the high gain jack as the first step up in volume is equivalent to about 45% volume from the iPhone HPO.

 

I also had a short audition with the iPhone 4 and the i.Fuzen HP-1 with a similar result of hearing an improvement, however the improvement was different.  While it was short, it sounded like the resolution was higher with the i.Fuzen and of course there was much more driving power and a slightly fuller, warmer sound.


Channel Imbalance: No

 

Hiss: None


Interference: None


Summary: The i.Fuzen is a great design and to my knowledge, the first amp built into a phone case.  The case doesn’t add much bulk to the iPhone 4/4S and is surprisingly light, but it the length it does add can be an issue for those with small pockets.  The added battery helps with iPhone life while powering the amp.  With performance that is an improvement with both headphones and IEMs, the i.Fuzen could turn your iPhone 4/4S into a high performing player both on the go and at home.  With a size increase that is much smaller than even the Pico Slim, the i.Fuzen offers a very strong performance for the size, and combining the price, it also excels in that area.  I have seen beefier cases and cases that provide less protection for the iPhone and the i.Fuzen does offer good protection and should prevent damage from most drops.  Overall with all things considered, Auzentech did a great job bringing this product to market, giving iPhone users something they can use to boost audio quality without adding too much bulk or wallet drain.

 

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Manufacturer: Furutech/ADL
Model: Cruise

Price: $475
Product notes: The Stride is available without the carbon fiber for $350.  Had issues with the fit of a Via Blue connector on an interconnect cable as the plug was nearly too large to fit in the jack.
Type: portable DAC/amp
Volume control: analog, dial
Power connector: USB (mini B)

Battery life: 80 hours (manufacturer spec).  I never ran out of battery life while using the Cruise.
Features:
- Auto-circuit disconnect when the headphone is not plugged in resulting in no audible noise and a 2 second delay before music starts playing

- Internal DAC, 24/96 USB
Works with 4 pin headphone plugs: Yes

Sound: With a very dynamic sound, the Cruise is spacious, punchy and exciting with a great sense of speed.  The brighter sound along with a slightly thinner note than the competition brings with it great detail and resolution as well as excellent imaging and transparency.  While the Cruise is on the brighter side in comparison with the amps reviewed here, it still has excellent deep bass and seems to slightly enhance the lowest octaves of the music.  With genres such as psy-trance and speed metal the Cruise has a speed advantage over other amps, and with genres such as live instrumental performances the Cruise can really bring out the details in the instruments and show top notch imaging. 

 

The Cruise isn’t the be-all end-all amp however as the hiss is noticeable upon first listen with many of my high sensitivity IEMs, however after a bit of time I don’t notice the hiss, well, unless I am focusing on the music and there is a gap between tracks or a quiet area of a song.  I was expecting a black background, but even though it doesn’t have one I still want to listen to the Cruise because of the rest of the presentation.  The most annoying thing for me, however, is if my phone is too close to the Cruise I will hear static and noise when the phone radio turns on.

 

Powering full sized headphones such as the LCD-2 and K701, the Cruise does well with plenty of power even though there is no gain switch.  Of course, none of the portable amps I have heard can make the LCD-2 sound as good as a desktop amp, but it does rank in the upper performance levels with the LCD-2 for a portable amp, and without the hiss issue.  The K701 sounds excellent from the Cruise with great detail, air and space.


Channel Imbalance: Yes, but barely audible with high sensitivity IEMs

Hiss: Yes, there is a continuous low level hiss with high sensitivity IEMs. 
Interference: Yes, some clicking with the iPhone 3G and some static/noise on the right channel with my Blackberry.  Phones must be 6” or further from the Cruise. ** Now fixed per Furutech.
Summary: While the shape isn't typical, it can still easily be strapped to your device and the carbon fiber finish of the Cruise looks stunning; it is the best looking amp I have seen (my pictures don't really show just how great it looks).  From a sound perspective it is difficult to fault the Cruise, but be prepared for a brighter sound to go with oodles of dynamics that lead to a punchy and fast sound.  The DAC section is as nice as the amp is, comparing similarly as to how the amp section performs.  Unfortunately with higher sensitivity custom IEMs there is a hiss present at all times, although it is not at a high level.  

 

 

Manufacturer Model Price Form Factor DAC Power Charge
Bit Depth Sample Rate
Furutec Cruise $450 Portable 24 96K Battery USB

 

 

Quantity Warmth Note Sustainment Smoothness Soundstage
Deep Bass Bass Mid-Bass Midrange Upper Mids Treble Width Depth Imaging
6 5 5 5 6 6 5 5 8 7 6 8

 

 

Bass Mids Treble Transparency Dynamics Resolution/ Detail Clarity Soundstage Score Total - Quality Hiss Imbalance Total Quality, High sensitivity IEMs
Quality Quality Quality
10 9 9 9 10 10 10 7.0 9.1 4.0 8.0 7.0

 

 

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Manufacturer: Just Audio

Model: uHA-120

Price: £199.86

Product notes: AHA-120 is the class A variant; Justin owns Just Audio and is not only personable, but very meticulous about his products. 

Type: portable amp

Volume control: analog, knob.  There is a volume pot upgrade that is more balanced at low volumes.   Justin has improved the grading for the standard volume pots which will give better balance results. 

Power connector: USB

Battery life: Up to 24 hours per the manufacturer

Features:
- Normal or fast charging - normal is for lower powered USB ports

- APSS (auto or battery) - when set to USB, the uHA will take power from the USB input vs. the battery, with more power output (28 mW @ 300 Ohms vs. 16 mW @ 300 Ohms when set to battery

- Adjustable gain via internal jumpers: 12 dB or 6 dB; tool and instructions included and Justin made a program that allows you to calculate the power output.

Includes: Tool to open the uHA-120 so you can change the gain

Specifications:

Maximum Continuous Power output:

                60 mWrms/channel into 32 ohm load (120mWrms total);

                28 mWrms/channel into 300 ohm load;

Distortion (THD+N): < 0.005% @ 1KHz (-16dBu to 5dBu output level)[1];

Dynamic range (dBA): 110dB

Bandwidth (-1dB): 10Hz-40kHz

Output impedance: < 1 ohm [2]

Output current limit: ~= +/-80mA per channel

Maximum Gain (REV B): 12dB || 6dB (based on jumper setting);

Battery recharge time (max): 2.5 hour fast charge; 6 hour normal charge;

Dimensions (approx): height=23mm; width=52mm; length=85mm

Weight = 125g +/-1g

Notes

[1] Tested using Beyerdynamic DT-311 (32 ohm) headphones;

[2] Actual measured output impedance < 0.1ohm; BW = 10Hz-40kHz with 2R2 load (100mV test level).

You can go to the specifications on the Just Audio site for charts.

 

Works with 4 pin headphone plugs: No

Form Factor: The uHA-120 uses a similar form factor to the Stepdance and Neco amps.

Sound Signature: I have spent much time thinking of what to write here, unsuccessfully and realized that the uHA rather just disappears.  It is very neutral and unobtrusive in sound, imparting less of a sonic signature on the music than just about all the other amps I have tested.  There is still a slight bump in the bass and treble with a little touch of warmth and a smooth presentation, but overall the uHA-120 is very neutral.

Sound Quality: The uHA stacks up well in the comparison, not giving the best performance, but not being outclassed with an overall sound quality score that is in line with the Pico Slim.  With great clarity, good resolution, and very good transparency delivered with a smooth and very enjoyable presentation I often forget about the uHA and just focus on the music I am listening to or headphone I am reviewing.  While I do forget about the amp, it doesn't give the liveliest presentation and is a bit below many of the other amps I have tested in soundstage width.

With headphones, the uHA has the least amount of headroom, however I did not adjust the internal gain, so the ability to play loud will improve.  However, the uHA did hold its own with headphones at volume levels I would listen at, which isn't all that loud.  The biggest issue is with high sensitivity IEMs, especially my custom IEMs as the uHA I have for review does have a fairly significant channel imbalance, not allowing me to listen at my typical quiet volumes except with a source that has its own volume control.  And the uHA doesn't pair well with every source, as with my modded iPod the uHA doesn't seem to perform as well as from the line out of the 801 or TTD V2.

Channel Imbalance: Yes, fairly significant with high sensitivity IEMs and mild with lower sensitivity IEMs.  No problem with most headphones.

Hiss: Not for typical use as there is hiss as the volume increases, and with the JH16 it was only evident at levels that are much too loud for any extended period of time.

Interference: No interference from both my Blackberry and my iPhone

Summary: The uHA is a capable performer that doesn't add anything to the signal path other than what it should: more power and control.  The transparency is very good as the uHA disappears and isn't noticed like other amps are, but the other amps get noticed for adding dynamics and punch, or giving a brighter or warmer sound, or even adding space.  The biggest issue with the uHA was the imbalance with high sensitivity IEMs, even on low gain.  There is an option for an upgraded volume pot, and I would like to hear that option some day.  I did often forget that the jack is not 4 pin compatible when used with something such as the Fabs.  All in all, if the balance issue was not present, the uHA would be a great amp for the price for IEMs.  As it stands, it is a very nice amp for headphones and a great, neutral choice that will allow you to experience your other equipment without concern of your amp adding its signature to the chain.

 

 

Manufacturer Model Price Form Factor DAC Power Charge
Bit Depth Sample Rate
Just Audio uHA-120 $310 Portable N/A N/A Battery USB

 

 

Quantity Warmth Note Sustainment Smoothness Soundstage
Deep Bass Bass Mid-Bass Midrange Upper Mids Treble Width Depth Imaging
6 6 6 6 6 6 6 5 8 5 5 5

 

 

Bass Mids Treble Transparency Dynamics Resolution/ Detail Clarity Soundstage Score Total - Quality Hiss Imbalance Total Quality, High sensitivity IEMs
Quality Quality Quality
8 8 8 8 6 8 9 5.0 7.6 10.0 2.0 6.5

 

---------------------------------

 

 

Manufacturer: Portaphile
Model: 627

 

P1020733.JPG P1020734.JPG P1020366.JPG P1020723.JPG P1020724.JPG P1020726.JPG

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Price: $550 + $10 US shipping and $25 international shipping
 
Size: 2.824' x 3.19" x .748"
 
Product notes: There is an audible noise when you turn the amp on and off.
 
Type: Portable amp
 
Volume control: Analog, knob
 
Power connector: Power Adaptor/Charger Included (5V), non-standard
 
Battery life: Powered by Single 3.7V Lithium Ion (Included, Rated for 500 Charges), Runs 4 Hours on a full charge, Battery charges in 2.5 Hours when Ampliifer is charged while off
 
Features:
- Three Channel Design, Isolated Output Ground, Four Layer PCB with 3 x OPA627 and 6xBUF634's, Jung Multiloop Topology, Elna Cerafine Caps
- External Hi/Low Gain Switch (7/2)
 
Works with 4 pin headphone plugs: Yes
 
Sound: The 627 was designed for sound quality first and foremost, and it shows.  The entire spectrum has a ‘naturalness’ to it, and a recreation of space with more layers and detail than any other amp I have heard in addition to being larger in all directions compared with any other portable amp I have heard to date.  It even improves upon the internal amp of the Anedio D1!  The bass control is the best I have heard, conveying a greater sense of power with more weight for bass heavy tracks, but it doesn’t sound enhanced, just more true to the recording.  Background bass lines are presented with excellent definition and the right amount of power, yet still remain in the background resulting in better realism.  While some BA driver IEMs don’t have great low volume bass performance, the 627 gives more oomph at lower volumes than other amps giving a better low volume listening experience.  But the 627 isn’t all about the bass; the midrange and treble are also extremely natural and effortless.  Space recreation within the midrange is exceptional with resolution that is a step above the competition.  When a headphone is capable of performing at a high level, the 627 will push the performance level further.
 
The 627 has no problem driving any of my custom IEMs, however with my ultra-sensitive CIEMs such as the DUNU DC4 I noticed all the noise that various players have which my other amps seem to not pass along.  This includes an electrical noise from my modded iPod 5.5G and hiss from the iPhone, but the 801 and DX100 are quite clean.  The 627 increases the soundstage size while improving the presentation focus along with better dynamics resulting in a more transparent and dynamic sound overall.  Testing with the HD600, Pro750, and LCD-2 V1, the 627 handled all quite well with very good control and enough power to drive even the LCD-2 without a problem.  While the 627 pushes the HD600 and Pro750 to higher levels than the other amps, the improvement isn’t as much as with the LCD-2.  Overall, clarity is noticeably improved for the headphones I tried to go with more impactful and prominent bass, but within the scope of the music.
 
Don’t expect to hook the 627 up to a low end headphone and get significantly better results.  When I paired it with an iPhone 4S I was rather disappointed in comparison with higher end sources, but when sourced from my modded iPod or something better driving a high end headphone the results were exceptional.  
 
Channel Imbalance: Essentially none unless you listen at extremely low volume levels to very high sensitivity IEMs
 
Hiss: The hiss that is present is the type that increases as you turn the volume up to dangerous levels, so it isn’t a factor for music playback unless you feed it a weak signal or ultra-quiet tracks you really need to turn up.
 
Interference: Slight (only audible between songs) with a Blackberry Bold sitting on top of the amp loading a web page
 
Summary: The Portabile 627 is simply the best portable amp I have heard to date period.  It can drive CIEMs to a higher level of performance and is the first portable that makes the LCD-2 sound as good as my desktop Anedio D1, and every other headphone/IEM I have thrown at also sounds great.  The 627 offers a very natural, layered, spacious, and controlled sound that is a pleasure to listen to.  It improves upon amp circuits in the DX100 and the 801 GAME card and outperformed other amps such as the Cruise, Stepdance, and Pico Slim in a convincing way when sourced well and feeding high end headphones/CIEMs.  The negatives are that the battery life is relatively short at around 4 hours, and the size, while not huge, is on the larger side of the spectrum.  You can use the 627 as a desktop amp with the included wall power adapter, and that might be a great idea for those that want both a portable and desktop amp!
 
Manufacturer Model Price Form Factor DAC Power Charge
Bit Depth Sample Rate
Portaphile 627 $550 Portable N/A N/A Battery Wall

 

Quantity Warmth Note Sustainment Smoothness Soundstage
Deep Bass Bass Mid-Bass Midrange Upper Mids Treble Width Depth Imaging
6 5 5 5 5 5 5 5 9 9 9 10

 

Bass Mids Treble Transparency Dynamics Resolution/ Detail Clarity Soundstage Score Total - Quality Hiss Imbalance Total Quality, High sensitivity IEMs
Quality Quality Quality
10 10 10 10 10 10 10 9.3 9.8 4.0 10.0 7.9

 

---------------------------------------

 

Manufacturer: Epiphany Acoustics

Model: EHP-O2

 

P1020735.JPG P1020737.JPG P1020393.JPG

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Price: £99.99 (~$157)
 
Size: 1 1/8” H X 4” D (with volume knob) X 4 1/4” W
 
Product notes: Based on the NwAvGuy O2 amp design
 
Type: Portable amp
 
Volume control: Analog knob
 
Power connector: Wall adapter, non-standard
 
Battery life: 8 hours
 
Gain: Adjustable 1, 2.5
 
Specifications:
- THD @ 1kHz: 0.0017%
- Noise level (ref 400mV): -105dB
- IMD: 0.001%
- Power output @ 33Ω : 641mW
- Crosstalk: 65dB
- Channel balance 0.6dB
 
Works with 4 pin headphone plugs: Yes
 
Overview: The O2 was designed by the controversial NwAvGuy who uses measurements as his de facto standard for gear and doesn’t rely on ears.  He wanted to make an amp that measures at least as good if not better than high end amps, but at a fraction of the price and make it public domain.  The amp was also designed to be used as a portable amp, and what really surprised me when I first saw the amp in person was the large size.  Due to the configuration, the amp is more of a transportable amp than a true portable in my opinion, but with the right cable, it can be strapped to a source and used on the go.  Just don’t expect it to go into your pocket unless you wear cargo pants.
 
There is an odd operating issue where the amp develops a cyclical popping when the battery is low due to the protection circuit turning the amp off when the voltage is low which increases the battery voltage, turning the amp back on.  And it clicks for every cycle.  If you hear that, you know it is time to charge the EHP-O2.  

 

Sound: Upon first listen with a BA CIEM, the O2 sounded quite good.  Switching to headphones, the HD600 specifically, I was impressed.  The O2 was performing well some issues came to light, especially when I started comparing it with some higher priced amps.  Notes are a little soft both on the attack and decay which results in a slightly slower sound with dynamics that aren’t quite up to par with most of the other amps I have.  This note thickness and the dynamics have a trickle-down effect on the realism and transparency as the headphones didn’t disappear quite as much as my other amps except the similarly priced Neco.  The spaciousness of the O2 is good, better than some more expensive amps, but the imaging is slightly below average (of more expensive amps), which seemed to be due to the attack/decay.  

 
I tried the O2 across a decent sized sampling of headphones, IEMs, and custom IEMs and it performed quite consistently across the spectrum, which is quite a feat.  The Neco, for example, can sound excellent with some CIEMs but poor with others, so the consistency is impressive.  When using the O2 with the TS842, the bass was quite good, but again, it doesn’t outshine the other amps.  With the Pro750, the presentation isn’t as smooth as many of the other amps.  BA CIEMs were all handled well and didn’t have issues that some amps can have.  On the flip side, the amp didn’t synergize with anything taking it to another level like the other amps can.  
 
The O2 is very transparent to the source, not adding coloration and when amped from a headphone out, it will retain the sound signature.  Comparing with the RoCoo BA internal amp*, the O2 performed similarly, but the BA internal amp was more 3D and a bit more musical.  But, the O2 sounded a bit better than the RoCoo P.  If you use a Clip+, getting the O2 will improve the bass performance a decent amount, but the improvements in the rest of the spectrum aren’t nearly as large.  Comparing with the amp in the D1 DAC, the O2 held its own from an authoritative standpoint, but the soundstage was constricted when using the O2.
* Not truly a fair comparison since the internal amp of the BA is fed by a line level input while the O2 was fed by the amp out.  I did this to see if the BA could be improved upon with an amp that cost less than the BA for desktop use.
 
Overall, the performance is about where an amp in this price range should be from a musicality standpoint, and technically it punches above its weight.
 
Channel Imbalance: At low volumes with high sensitivity IEMs such as the JH16 and AM4 pro.
 
Hiss: None
 
Interference: None
 
Summary: The O2 amp performs well for its price point with some very good qualities including source transparency, the ability to be consistent across a wide range of headphones, and very good soundstage space.  It competes technically in driving power and soundstage space with more expensive amps, but due to attack and decay being slightly slow, the musicality isn’t quite on par.  It is a versatile amp that will give a consistent experience and is an excellent performer for the price.  My comparison with higher priced amps is not really fair, and performance is very similar to the Neco, which is in the price ball park.  The size of the O2 isn't ideal for portable use and the orientation of the input/output makes it difficult to attach to my iPod/iPhone.  The bottom line is if you want very good, consistent performance across a headphones and IEMs, for desktop/transportable use the EHP-O2 is a great chose at the price point.
 
Manufacturer Model Price Form Factor DAC Power Charge
Bit Depth Sample Rate
Epiphany EHP-02 $160 Portable N/A N/A Battery Wall

 

Quantity Warmth Note Sustainment Smoothness Soundstage
Deep Bass Bass Mid-Bass Midrange Upper Mids Treble Width Depth Imaging
6 5 5 5 5 5 5 4 7 7 5 4.5

 

Bass Mids Treble Transparency Dynamics Resolution/ Detail Clarity Soundstage Score Total - Quality Hiss Imbalance Total Quality, High sensitivity IEMs
Quality Quality Quality
8 8 7 6 6 7 7 5.5 6.8 10.0 10.0 8.9

 

---------------------------------------

 

Manufacturer: Headphonia
 
 P1020718.JPG P1020376.JPG P1020373.JPG P1020721.JPG P1020711.JPG
Click on an image to enlarge
 
Price: $299.00
 
Size/Weight: 8.5mm x 56mm x 98mm (0.33'' x 2.20'' x 3.86''); 75g
 
Type: Portable amp, slim design
 
Volume control: Analog wheel
 
Power connector: USB Mini-b
 
Battery life: 80 Hours Play Time in Lowest Power Mode (no voltage boost);  30 Hours Play Time in Highest Power Mode (12V) (High-Capacity 1200mAh/4.2V Lithium-Ion Battery)
 
Features:
- Automatic Power Adaptation with up to 12V Internal Voltage
- Maximal 11V Output Voltage (Peak to Peak)
- Three Selectable Gain Settings (2dB, 9dB, 18dB)
- Bass Boost (0dB, 3dB, 9dB)
- Treble Boost Switch
- Öhmann Crossfeed (Off, Low, High)
- Automatic Power Switch
- Easy Battery Replacement without Soldering
- Symmetric & Short Audio Paths with Low Noise
- Analog Audio Input Jacks on Both Ends 
- Two Headphone Jacks
- ALPS Analog Volume Potentiometer
- Low-Battery Indication (Slow and Fast LED Blinking)
- 4-Layer Circuit Board with two Ground Planes for Low Noise
- Black Anodized Aluminium Case with Laser Engraving
- Aluminium End Panels with White Silk Print
 
Works with 4 pin headphone plugs: Yes
 
Sound
IEMs: The 4G performed anywhere from well to satisfactory with my IEMs and custom IEMs as it is overall noticeably better than the 12HE Arrow I own and on par to superior with the Pico Slim, and you can even get the sound signatures to be similar with the treble boost.  The amp is on the warmer and thicker side of things with the knobs in the off positions, and when paired with a headphone that changes with the source and track such as the Spiral Ear SE 5-way, the sound is thicker than with other amps.  However, while the NT-6 is also source dependent to an extent, there wasn’t any additional thickness due to the Arrow.  Detail/resolution of the 4G is close to the competition, but the 4G falls slightly behind the EPH-02 and Cruise in instrument separation.
 
Headphones: The 4G sounded more open and transparent with the HD600 than the Stepdance, EPH-O2 and about on par with the Neco V2.  Overall, the HD600 sounded quite good with the 4G, but the bass wasn’t as tight as with some other amps.  When paired with the Pro750, the bass response was quite enhanced as the bass wasn’t as controlled as with some of the other amps such as the Stepdance and O2.  The overall presentation was smooth in comparison with the EPH-O2, Neco V2, and Pico Slim while about on par with the Stepdance.
 
The Arrow has bass boost and treble boost, so you can easily adjust the sound depending on your preferences and headphones you are listening to.  The quality of the boost on the first setting is excellent and still good on the second setting, but it does depend on the attached headphones.  For example, with the bass boost at II, it is easy for a bass driver to get overloaded and distort, or if your headphones can handle it, you will have a bass monster on your hands!  But, the boost is more of a upper bass boost than a deep bass boost.  Similarly, with the treble at II, the treble can sound too emphasized and emphasize weaknesses of the treble of the attached headphones/IEMs.
 
Compared with the 12HE, the 4G performs at a much higher level, but the sound signature is retained.  The sound is more refined and transparent with better transparency, detail, and overall note quality.  The imbalance of my 4G unit at low volumes is worse than that of the 12HE, and the 12HE is more resistant to interference, but other than that the 4G improves upon the 12HE in every way.
 
Since both the Pico Slim and Arrow offer exceptional portability, I have decided to compare the two head-to-head.  First, the Arrow has many more options than the Pico Slim including bass boost, crossfeed, treble boost, and gain settings.  The 4G can drive full sized headphones more cleanly and to louder volumes.  With IEMs, the 4G has a wider soundstage with similar depth, a smoother treble, and a more open sound overall due to the larger presentation space.  The 4G is also warmer with more bass oomph and focus, but with the treble boost on I, the 4G has a similar treble response, but the treble is still smoother.  Detail levels are similar, but the 4G is more effortless and slightly more transparent.  The Pico Slim beats the 4G in volume balance, as the 4G has some issues with very high sensitivity IEMs (although Robert can adjust the gain for you and basically eliminate any imbalance), and in interference, as the PS has none while the 4G is affected by the Blackberry and iPhone 4S (but not 3G).  The iPhone interference is a killer if you plan on using the 4G with a 4S. 
 
Channel Imbalance: Yes, with high sensitivity IEMs at very low volumes.  Robert can adjust the gain for high sensitivity IEMs.
 
Hiss: None
 
Interference: Yes, when my Blackberry is within 2 feet of the amp, but there is no interference with my iPhone 3G but there is static interference with the iPhone 4S.
 
Summary: The Arrow 4G has a great form factor and the best feature set I have come across in an amp including auto power on/off, switches including gain, bass boost, treble boost, and crossfeed, two headphone outputs, USB charging, plus it sounds great.  The switches allow you to easily change the sound signature of your headphones/IEMs which is a nice feature.  It is a competes and beats the Pico Slim in many ways, however there is a huge issue for on the go use with a phone: interference.  The 4G would be an unconditional recommendation due to the size/price/performance if I didn’t have to keep my Blackberry on the other side of my desk to avoid hearing when its radio is on.  If you pair it with a device that won’t cause interference, then the Arrow 4G is a winner.
 
Manufacturer Model Price Form Factor DAC Power Charge
Bit Depth Sample Rate
Headstage Arrow 4G   Flat N/A N/A Battery USB

 

Quantity Warmth Note Sustainment Smoothness Soundstage
Deep Bass Bass Mid-Bass Midrange Upper Mids Treble Width Depth Imaging
5.5 6 6 5 5 5 6 6 7 8 5 4.5

 

Bass Mids Treble Transparency Dynamics Resolution/ Detail Clarity Soundstage Score Total - Quality Hiss Imbalance Total Quality, High sensitivity IEMs
Quality Quality Quality
8 8 8 8 8 9 8 6.2 7.8 10.0 7.0 8.3

 

---------------------------------------

 

 

Manufacturer: Shonyun

Model: 306

 

      

    

 

 

 

Price: $180 on ebay

 

Product Overview: The amp is on the larger side for a portable amp as it is larger than the Neco V2, especially in length, but slightly smaller than the EHP-O2.  The body of the unit uses an anodized brushed metal finish that looks nice but does scratch relatively easily.  The face plate looks great and is finished much better, and the volume knob is solid.  The 306 uses two AD8397ARDZ (with a high slew rate, high-bandwidth), Japan KOA high precision metal film resistors, WIMA capacitors, ELAN fever electrolytic capacitor, KOA metal film SMD resistors, and has five built-in 3.7V lithium batteries to stabilize operating voltage.  There is a single input and single output on the front panel.

 

Size/Weight: 110mm * 70mm * 25mm
 

Type: Portable amp
 

Volume control: Analog knob
 

Power connector: Wall adapter, non-standard (24V)

 

Battery life: Approximately 12 hours

 

Features:

- Frequency response:10-100KHz

- Output power: 120mW

- Signal to Noise Ratio: 105dB

- Distortion: <0.005%

- Charging adapter: 24V-500mA

- Suitable impedance: 16 ~ 300Ω

- Input impedance: 47KΩ

- Output Current: 600mA

 

Works with 4 pin headphone plugs: Yes

 

Sound: The 306 is a fairly neutral amp, with a bit less bass weight and a slight bit more treble than the two competing amps I have in the price range, the EHP-O2 and Neco V2.  The 306 is typically more natural sounding in the treble region, however the overall performance relative to the other amps does vary with different headphone pairings.  One of the largest differences between the 306 and other amps in the price range, including the uHA-120 is the refinement of the presentation, which is quite good for the price. 

 

Comparing the amps with headphones, dynamic driver IEMs and the EarPods, the 306 had slightly less control of the bass driver even though the presentation had the least amount of bass in comparison.  Moving up from the bass, the 306 was more refined at times depending on the headphone.  The 306 has plenty of power to drive headphones, but it doesn’t drive power hungry headphones such as the LCD-2 all that well, which is no different than most portable amps, even those that cost well over double. 

 

The better the source, the better the 306 will perform, but it does better with lower quality sources such as the iPhone 4S than the EHP-O2 and most of the time the V2.  As you go up the source chain, the 306 can reproduce more detail and present a larger space and has an overall more refined presentation than the other amps.

 

One of the difficult things in comparing amps is performance differs depending on the headphone and source paired with them, making the chain very important.  I have included the 306 in the source matching section of several of my CIEM threads, which might help with some reference points.

 

 

I tested the 306 with the HD600 and AKG K550.  With headphones there are is no hiss like there can be with my CIEMs.  The 306 does extremely well with both the HD600 and K550, controlling the low end quite well, recreating very good space, and articulating detail.  Compared with the uHA-120 (low gain mode), the 306 controls the bass better, which has a trickle-down effect making the rest of the spectrum cleaner, and the soundstage is a bit more expansive.  Compared with the O2, the HD600 sounded more dynamic and more forward, but control was similar.  With the K550, the bass was equally controlled, but the rest of the spectrum was smoother with the 306.  The Stepdance is a bit brighter than the 306, but the treble is also not quite as smooth as that of the 306, however the overall sound from the SD is a bit more natural sounding.  Moving to the HD600, the SD is still a bit more natural with more depth to the presentation, but the differences aren’t huge.  Note that I had to use an adapter for my 1/4” to 1/8” adapter due to the recessed plugs in the 306.


Channel Imbalance: Yes, with moderate sensitivity IEMs at lower volumes; more severe with higher sensitivity IEMs and at very low volumes.

 

Hiss: Yes, with high sensitivity IEMs.  Hiss increases as the volume is increased.
 

Interference: None
 

Summary: The Shonyun 306 is an extremely refined amp for the price range and has a lighter, leaner sound signature.  There is a balance across the frequency spectrum, but the bass isn’t quite as prominent as with the Neco V2 or EHP-O2, however the imaging is better than the other two.  Depending on the source and headphone matchup, the 306 can be a fantastic performer for the price point.  It is larger than many other portable amps, but smaller than the EHP-O2 and slightly larger than the Portaphile 627.  The 306 is recommended due to the refinement, smoothness, imaging and natural sound, but be sure you are OK with a slightly lower bass presence than other amps in the price range, slight channel imbalance at low volumes, and hiss with high sensitivity IEMs.

 

When used with headphones, at least the ones I tried, the 306 was quite impressive and is definitely worth the price.  The open sound and controlled bass work well and there is plenty of power for headphones.  You can do better at higher prices, but the differences with the HD600 and K550 weren’t huge to me.

 

Manufacturer Model Price Form Factor DAC Power Charge
Bit Depth Sample Rate
Shonyun 306 $180 Portable N/A N/A Battery Wall

 

 

Quantity Warmth Note Sustainment Smoothness Soundstage
Deep Bass Bass Mid-Bass Midrange Upper Mids Treble Width Depth Imaging
5 5 5 5 5 5 5 5 6 6.5 5 5

 

 

Bass Mids Treble Transparency Dynamics Resolution/Detail Clarity Soundstage Score Total - Quality Hiss Imbalance Size/ Portability Total Quality, High sensitivity IEMs
Quality Quality Quality
7.5 8 8 6 7 8 8 5.5 7.1 6.0 6.0 3.0 5.5

 

--------------------------------

 

Manufacturer: JDS Labs

Model: O2 + ODAC, separate units

 

     


Price: $139.99 + $149.00
Options: Different amp gain settings; Black or silver cases; RCA output option for ODAC

Product notes: JDS Labs offers the O2 + ODAC Combo for $279.99, which is an integrated unit that has both the O2 amp and ODAC DAC, but no battery.  It does require external power for the amplifier section.  Performance should be very similar to this test setup.
Type: DAC/amp (separate or integrated)
Volume control: Analog
Power connector: DAC: mini USB; amp: custom wall adapter

Battery life: O2 amp - 6-8 hours; ODAC - N/A; ODAC + O2 combo – N/A
Features:
- Alps Dual Analog Potentiometer

- Dual Gain Switch (2.5x and 6.5x)

- Opamps: JRC NJM2068D, 2x JRC NJM4556AD

- AC Jack - Rechargeable 9V NiMH Batteries
Specifications, O2 amp:

- Frequency Response: +0.01, -0.01 dB (20Hz-20kHz)

- THD 1 Khz 150 Ohms: 0.0016%

- IMD CCIF 15 Ohms: 0.001%

- IMD SMPTE: 0.002%

- Noise (ref 400 mV): -105 dB

- Max Output (33 Ohms): 613 mW

- Output Impedance: 0.54 Ohms

- Crosstalk (15 ohms): 65 dB

- Channel Balance (at 50% volume): 0.6 dB

- Gain: 2.5x and 6.5x

- Volume Potentiometer Taper: 15A or 3B

- Case Dimensions (mm): 108.50 x 80.00 x 29.50 (excludes jacks)

- Case Dimensions (inches) = 4.27 x 3.15 x 1.16" (excludes jacks)

- Battery Run-time: 6-8 hours

- Weight: 11 oz, with batteries 

Specifications, ODAC:

- Frequency Response: +/- 0.1 dB (10 hz – 19 Khz 24/44)

- THD+N 100 hz 0 dBFS: 0.0029%

- THD+N 20 hz –1 dBFS: 0.003%

- THD+N 10 Khz –1 dBFS: 0.003%

- IMD CCIF 19/20 Khz –3 dBFS: 0.0011%

- IMD SMPTE –1 dBFS: 0.0004% A

- Noise A-Weighted dBu 24/44: --102.8 dBu

- Dynamic Range: > 110 dB A-Weighted

- Linearity Error -90 dBFS 24/44:      0.0 dB

- Crosstalk 0 dBFS Line Out 100K: --93.5 dB

- USB Jitter 11025 hz J-test 24/44: Excellent

- Maximum Output Line Out 100K: 2.0 Vrms

 -Distortion: < 0.005%

- PCB Dimensions: 49.0 x 58.0 mm

- Weight: 2oz

- Standard Case Dimensions: 53 x 62 x 13mm

 -RCA Case Dimension: 99 x 63 x 13mm

- Audio Formats: 16/44, 16/48, 16/96, 24/44, 24/48, 24/96

- Interface: USB, Audio Class 1

- Native Driver OS Support: Windows XP & Later, OS X x86, Linux

Works with 4 pin headphone plugs: Yes

Sound:

JDS Labs is one of the manufacturers of the NwAvGuy O2 amp and ODAC, which JDS sells both separately and as an integrated unit.  I was interested in testing this combo so John agreed to send me both the ODAC, but I thought I should test it with his O2 amp even though I have the Epiphany EHP-O2 amp.  Both O2 amps were built to the original specification according to the manufacturers, so this was a good opportunity to look for consistency as well estimate how an integrated unit, called the ODAC + O2 combo, would perform.

 

The ODAC is USB powered with native Windows drivers that allow volume control, which came in handy when I initially tried the ODAC & O2 together in high gain with the HD600 as the output was distorted at 100% volume.  Switching to IEMs yielded the same results.  After talking a bit with John, there is a known issue with the O2, but it shouldn’t have been as bad as I experienced, and when I tried to replicate it after a full charge, the issue had disappeared.

 

Comparing the two amps provided interesting results, as the JDS amp was louder at the same volume than the EHP on low gain, but the same on high gain with the HD600, but as I used higher and higher sensitivity CIEMs, the volume became closer and closer.  With the HD600 the JDS O2 amp was louder by about 1/4th of a turn on the volume knob, as the sensitivity increased, the difference became negligible.  The difference was still quite noticeable with the IE800, less with the SM64, even less with the aud-8X, and none with the Fit-Ear PS-5.  In high gain mode there were no volume differences and the sonic differences were negligible. 

 

Also, they both sounded different when volume matched in low gain with the HD600 as the EHP-O2 had slightly superior imaging while the JDS O2 was more dynamic, slightly more detailed, and the treble was presented a bit more forward.  But the differences were dependent upon the headphone and most IEMs performed similarly.  Some of the exceptions included the Spiral Ear SE 5-way Reference, which had much more pronounced deep bass with the JDS O2, and the NT-6 pro, which was brighter, less smooth, and had less bass weight with the EHP-O2.  The HD600 sounded more natural in high gain mode than in low gain mode, but the low volume channel imbalance didn’t allow proper testing with my CIEMs with high gain.

 

Talking with the manufacturers, the gains were the same, so I took the amps apart to see if there were any physical differences.  There were some differences: the EHP uses 8.4V batteries while the O2 had a battery that said 9V and measured 8.78V after hours of use.  John told me the batteries he uses are the best available and better than the 9.6V 230 mAh rechargeable batteries I inquired about.   There are also some differences in resistors as the EHP-O2 didn’t have all the resistor spaces filled while the JDS O2 did.  The EHP amp had the chips soldered to the board while the JDS uses IC sockets for the op amps and the main AC coupling capacitors are different brands.  After further discussion as to the differences between the amps, John thought it was related to the AC coupling caps.

 

Next, I compared the ODAC + O2 with other portable DAC/amps even though the integrated combo is not portable.  My first comparison was with the smaller, similarly priced Leckerton UHA-6S MKII with stock op amp that is very popular and can be used with a computer or Android device.  Sonically, the O2 + ODAC combination has a smoother, more organic and spacious sound compared with the more analytical and slightly more detailed Leckerton.  The O2 + ODAC paired better to my ears with more analytical IEMs while still offering a more natural, although less clear and concise presentation with warmer and thicker headphones such as the LCD-2 and 5-way reference.  Sourcing the Leckerton amp from the ODAC resulted in higher performance than the ODAC combined with the O2, or the Leckerton using its own internal DAC via USB. 

 

The ODAC outperformed the HUD-MX1 as it details were more articulated while there was a more dynamic presentation with better imagining, cohesiveness, and a larger space.  The ODAC outperformed the UHA-6S MKII internal DAC in spaciousness, instrument separation, and detail levels, and also bested the internal DAC in the Cruise with better resolution, detail, spaciousness, and imaging.  I decided to see if this DAC was a true giant killer by comparing it with the Anedio D1 DAC and found the difference much smaller than the price would indicate, although the D1 is more resolving, spacious, clear, and concise.  Pairing the ODAC with the Ortofon MHd-Q7 amp showed off the ODAC’s capabilities as the Mhd-Q7 presented a more detailed, spacious, and dynamic sound with accurate PRaT, and the performance improved more with other amps such as the Lear FSM-02 and Portaphile.

 

Using the ODAC + O2 combo on my desktop with many different headphones, IEMs, and CIEMs left me respecting this combo for its ability to pair well with just about everything and never sound fatiguing or harsh.  The O2 couldn’t quite do justice to the bass region of the LCD-2, but it still performed well overall.  The O2 was able to drive even some of my finicky CIEMs well with complex and/or low impedance curves, which I can’t say about most amps in this price range.

 

Overall, the JDS O2 is a small step up in performance compared to the EHP-O2 previously reviewed and the spacious and organic sound with good dynamics performs well for the price.  The sonic weakness is the detail levels of the amp, which aren’t as resolving as some of the other similarly priced amps.  The ODAC is an excellent little DAC with excellent performance for the size, and is even more impressive given the price.  The negatives of the O2 amp are the same as previously stated: large size with input/output ports that make portable use difficult and non-standard charger.  Combining the ODAC in the same chassis and the non-standard power adapter is mandatory to enjoy the excellent sounding combo.


Channel Imbalance: Yes, with high sensitivity IEMs at very low volumes.

Hiss: Slight with high sensitivity IEMs; increases as volume knob is turned up.
Interference: None.

Noise when turned on/off:
Summary: With a natural sound that is spacious and dynamic presentation with great imaging, the JDS Labs O2 amp is quite capable with a wide range of headphones and IEMs.  Detail levels, while not bad, are bested by some other amps in the price range, but that doesn’t stop the O2 from being a great buy.  Form factor is bulky for portable use, but on the desktop the O2 is great for the price.  Performance of the ODAC is exceptional for the price, besting the built-in DACs in the portable DAC/amps I have and performing closer than anticipated to the Anedio D1 DAC.   The integrated ODAC + O2 combo I simulated is an excellent sounding and performing desktop only solution that can drive just about anything you throw at it.  Even though the amp section hold the DAC back a bit, it is still a great value.

 

 

Manufacturer Model Price Form Factor DAC Power Charge
Bit Depth Sample Rate
JDS Labs O2 $140 Portable N/A N/A Battery Wall
JDS Labs ODAC $179 Portable DAC 24 96K USB N/A
JDS Labs ODAC + O2 combo $280 Desktop 24 96K Wall/USB N/A

 

Quantity Warmth Note Sustainment Smoothness Soundstage
Deep Bass Bass Mid-Bass Midrange Upper Mids Treble Width Depth Imaging
6.5 5 5 5 5 5 5 6 7 7 5.5 6.5
5 5 5 5 5 5 5 5 9 8 8 9
6 5 5 5 5 5 5 6 7 7 5.5 6.5

 

Bass Mids Treble Transparency Dynamics Resolution/Detail Clarity Soundstage Score Total - Quality Hiss Imbalance Size/ Portability Total Quality, High sensitivity IEMs
Quality Quality Quality
8 8 8 7 7 7 7.5 6.3 7.3 8.5 8.0 2.0 6.5
9.5 10 9 10 9.5 9.5 9 8.3 9.3 N/A N/A 10 N/A
8 8 8 7 7 7 7.5 6.3 7.3 8.5 8.0 N/A N/A

Edited by average_joe - 7/16/13 at 10:54pm
post #2 of 279
Thread Starter 

Amps reviewed in this post:

-          Lear FSM-02 v2

-          Ortofon MHd-Q7 

-          Leckerton UHA-6S MKII

-          Sunrise Ray (in review queue)

-          Sunrise Dolphin (in review queue)

-          Shonyun 306a (in review queue)

 

See the first post for additional amps and other information.  Check here for select review previews.

 

 

Manufacturer: Lear
Model: FSM-O2 V2

 

   

 

  

 

Price: HKD 2,998 + HKD: 200 for shipping ($412 USD shipped)
Product notes: Available in black or silver.
Type: Portable amp
Volume control: Analog knob, stud type (notched steps)
Power connector: USB; 5V-18V external power

Battery life: About 10hrs up @ front output, about 4hours @ Back Class-A output
Features:
- Two independent built-in amplifier circuits: independent output MOSFET CLASS-A and replaceable op amp design.

- Hardware EQ with three settings: high EQ, low EQ, hardware ByPass (skip EQ)

- Three gain settings

- Built-in 3000mAh USB rechargeable lithium battery

- Supports external power supply from 5V to 18V DC

- Ultra-low output impedance of 0.04 Ohm with the ability to drive headphones ranging from 8 Ohm to 600 Ohm
Specifications:

Frequency Response: 4Hz ~ 100 kHz (20Hz ~ 20kHzEQ = Flat +-0.002dB)

Output:

0.001% THD + N 16mW @ 15ohm (OPA2227 L GAIN) Internal Battery

0.001% THD + N 25mW @ 300ohm (OPA2227 L GAIN) Internal Battery

0.001% THD + N 14mW @ 600ohm (OPA2227 L GAIN) Internal Battery

S / N ratio: 100dB A-Weighted

Noise Level: 100nVrms @ L Gain A-weighted

THD + N Distortion: 0.00001% @ 1kHz @ 1Vrms (L GAIN no Load)

IMD Distortion: 0.0001% CCIF; 0.001% SMPTE 100 @ 1Vrms (Lgain no Load)

Output Impedance: 0.04 Ohm

Crosstalk: 90dB (no Load @ 10kHz) 62dB (@ 15ohm Load @ 10kHz)

Charging time: About 5hrs (DC 5V, 500mA)

Charging: DC5 ~ 5.5V (MAX)

EXT Power: DC9V ~ 18V (MAX)

Dimension: 57mm x 105mm x 24mm

Works with 4 pin headphone plugs: yes

Channel Imbalance: Yes, with very high sensitivity CIEMs 8/10

Hiss: Only with extremely high sensitivity CIEM that hisses with everything 10/10
Interference: None

Noise when turned on/off: Thump when turning on and off.  Class A circuit has electrical noise for the first minute of operation.

 

Sound:

The Lear FSM-02 v2 starts with impressing with specifications and features, which includes two full amp circuits and a hardware EQ.  The amp isn’t the smallest or thinnest, but the flat side and subtle curves help make it easy to use on the go with my iPod, iPhone, or any other device, although it is large for something like a Nano.  It isn’t the most stunning in the looks department, but the brushed aluminum finish is well done.  With plenty of switches, some located in difficult to get to places when the amp is connected, the amp doesn’t look like a work of art.  But, my main criteria for an amp is sound quality, and I would suggest continuing to read…

 

There are two amp circuit options for the FSM-02 v2: the op amp section which comes with the OPA2227 installed and has a 10 hour batter life, and the class A section with 4 hours of battery life.  I compared the FSM-02 v2 with several amps including the Portaphile 627, Ortofon MHd-Q7, Leckerton UHA-6S MKII (AD8610ARZ op amp), Meyer Audio Stepdance, HeadAmp Pico Slim, Headstage Arrow 4G, ADL Cruise, Just Audio uHA 120, and Sunrise Dolphin.  Many headphones were used in my evaluation, a list that is much to long to list, but includes the Audeze LCD-2, Sennheiser IE800, Spiral Ears 5-way Reference, Custom Art Music One, Dream Earz aud-8X, Fit Ear PS-5, Sennheiser HD600, AKG K550, Etymotic ER4P, and many more.

 

The op amp section performed quite well with a spacious, detailed, natural, and neutral sound.  Elaborating on the neutral sound, many other amps sounded slightly colored in comparison, such as the Dolphin and Pico Slim due to a bit more emphasis in the treble region, or the Arrow with added warmth.  Note decay is not too smooth and not too analytical, falling between the more analytical UHA-6S and smoother MHd-Q7.  Compared with the Stepdance, which I have found performs great in so many regards, didn’t sound as natural, open, or effortless as the Lear.  Amps often have synergy with select headphones, but the FSM-02 v2 paired well with everything and had less variation than I am used to.  Certain headphones did vary in performance from amp to amp such as the aud-8X, LCD-2, IERM, and to an extent Proguard P2+1.  Technically, the op amp section outperforms all but two of the amps I used for comparison: the Ortofon and Portaphile.

 

The built in EQ boost either bass or treble to suite different headphones with two three position switches for selection.  The selection is more difficult than it has to be as one switch between the input and volume knob must be either in the “BP” for bit perfect position for no EQ or the upper “EQ ON” position for the EQ to work.  Setting the switch to the middle position results in no sound, and I had trouble changing the switch without disconnecting the source cable.  If the switch is in the “BP” setting, the EQ 3 position switch still affects the sound, as setting “1” or 2” lower the volume.  When the switch is in the “EQ ON” position, the EQ switch must be in either the “1” position for bass boost or the “2” position for treble boost.  If the switch is in the “0” position for no EQ, there is no sound.  Using the EQ in position “1” warmed up the sound quite a bit, adding a richness to the single BA Music One and multi-BA LCM-5 without adding any distortion but the bass became too much with the IE800 and Lime Ears LE3b.  With the switch in the “2” position, some headphones improved while others didn’t.  For example, there wasn’t much of a difference between with the IE800 or Lime Ears LE3, although the LE3b did become clearer.

 

Normally, an amp review would be complete at this point, but the FSM-02 v2 has another amp circuit to test, the Class A portion.  This circuit is a real winner, adding dynamics and punch along with a more spacious and refined presentation adding to the already high performing, musical sound of the op amp output.  Every headphone I paired with it sounded natural and the overall performance closed in on the Portaphile 627.  While it doesn’t quite reach the same technical performance of the 627, it does have a lower noise floor, smaller size, similar battery life, and lower price.  With realism that is on par, but with a bit smaller and slightly less dynamic presentation, the FSM-02 v2 is quite impressive.  The EQ function works like it does via the op amp circuit, but the bass boost isn’t quite as significant and the clarity boost adds a bit more clarity while retaining a more refined and smoother treble.  For example, both the Lime Ears LE3b and Music One became clearer with the clarity boost on.

 

Using the medium gain with the LCD-2 and HD600 headphones did not change the sound quality from either amp circuit, but when using the high gain the presentation space became ever so slightly larger.  The amp was loud enough for my listening volume on low gain with all the headphones I tested.  I didn’t try the amp with an external power source, although it can accept up to 18V.  I also didn’t try changing op amps, and Lear is developing new op amp modules.  The power LED is bright when in class A mode, which may annoy some people, although the blue LED when the op amp section is on isn’t nearly as bad.


Summary:  The Lear FSM-02 v2 is an exceptional amp that offers quite a few options combined with competitive sound from the op amp section and class leading sound from the class A amp section, with performance that approaches that of the Portaphile 627.  Features include a built in EQ with a bass or treble boost, the ability to change op amps, and an input for an external power supply up to 18V.  Not the smallest in size, the curves and flat side help the amp pair well with iPods and phones.  Battery life is OK with the op amp output, registering about 10 hours, but the 4 hour class A battery life is a bit on the short side, although it is simple to just plug the amp in to any USB port for charging.  Overall, the Lear FSM-02 v2 is an exceptional amp and an exceptional value when the features and performance are taken into account.  Highly recommended!

 

 

Manufacturer Model Price Form Factor Power Charge Option Interference 4 Pin Compatible

Lear

FSM-02 v2 $412 Portable Battery USB Class A None Yes
Lear FSM-02 v2 $412 Portable Battery USB op amp output None Yes

 

Quantity Warmth Note Sustainment Smoothness Soundstage
Deep Bass Bass Mid-Bass Midrange Upper Mids Treble Width Depth Imaging
6 5 5 5 5 5 5 5 9 8.5 8.5 9
6 5 5 5 5 5 5 5 7.5 8 7.5 9

 

Bass Mids Treble Transparency Dynamics Resolution/Detail Clarity Soundstage Score Total - Quality Hiss Imbalance Size/ Portability Total Quality, High sensitivity IEMs
Quality Quality Quality
10 10 10 10 10 10 10 8.7 9.7 10.0 8.0 4.0 7.9
9.5 9 9 9.5 9 10 9.5 8.2 9.0 10.0 8.0 4.0 7.8

 

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Manufacturer: Ortofon
Model: MHd-Q7

 

 

  

 

  

 

Price: $398
Type: amp
Volume control: Analog with integrated power switch.
Power connector: USB Mini-b

Battery life: Approximately 18 hours (3 hour charge time)
LED lights: Green power, red charge.  Low brightness.

Works with 4 pin headphone plugs: Yes

Channel Imbalance: None

Hiss: Yes, noticeable with moderately sensitive IEMs and minimal with dynamic driver IEM; no change with volume changes.  Score: 4.5/10
Interference: None

Noise when turned on/off: Audible click on turn on, slight noise on turn off

 

Stylish looks and modern design exemplify the exquisite Ortofon MHd-Q7 amp that is brick shaped and slightly smaller in size than amps such as the Just Audio uHA-120 and Meyer Audio Stepdance.  The all-day plus battery life, convenient USB charging, slow adjusting volume control, and LED that isn’t too bright show that the looks and style were well thought out.

 

Comparing with lower priced amps and some of the older generation stalwarts such as the Stepdance and Pico Slim, the Q7 sounded extremely natural and more spacious with a good balance across the spectrum, with the tonality falling between the Stepdance and brighter Pico Slim.  Bass reaches deep and treble has good extension, dynamics are very good, and note weight strikes a fantastic balance between analytical and liquid, retaining detail while avoiding an analytical presentation that is musical and transparent.  In comparison, the ADL Cruise is more analytical with sharper notes, especially in the treble region, accentuating the refinement and natural presentation of the Q7 as a result.  While as spacious as the Headstage Arrow 4G is, the Q7 presentation is slightly more laid back but has better presentation depth for a more 3D sound with similar resolution but better instrument separation resulting in a cleaner sound.  The deep bass of the Q7 is more prominent and powerful than that of the Arrow 4G.

 

The Leckerton UHA-6S MKII (with default op amp, compared using the DX100 line out) is more analytical with more etched notes that decay quicker while the instrument separation and overall size of the presentation is smaller, resulting in a sound that isn’t quite as open, clear, or resolving as the Q7.  Compared with the StepDance, the Q7 has a bit more neutral bass response with similar dynamics, but the overall presentation of the Q7 is more natural, effortless, dynamic, and is smoother while presenting with more openness, air and separation.  The Lear FSM-02 V2 op amp output is very similar in performance, but the Q7 is a bit more dynamic with a better midrange while the FSM bass is slightly more controlled.  When comparing the class A output of the FSM, the Q7 does fall behind mainly due to the more open, larger sound of the FSM, but both have a naturalness to them that is special.  The Portaphile 627 widens the small gap between the Q7 and FSM with more space and fluidity.

 

Maximum volume on the Q7 isn’t very loud in comparison with the other amps used for comparison, and there is no gain switch, which could be an issue with low sensitivity headphones, especially full sized ones.  All line level sources I have were fine with the Q7, and the slow adjustment of the volume control is preferred over channel imbalances present with other amps when trying to listen at low volumes from a fixed output source. While the volume control is very good for high sensitivity CIEMs, the hiss makes pairing with higher sensitivity CIEMs problematic if you are sensitive to hiss.  For example, hiss wasn’t really an issue with a IEM/CIEM such as the Music One, LE3, or IE800, but with something like the JH16, NT-6, or LCM-5 the hiss between songs was distracting for me.


Summary: The Ortofon MHd-Q7 amp combines simplistic ease of use with unique stylish lines and a natural, neutral, spacious, and dynamic sound that is a winning combination when paired with the right sensitivity headphones in any price range.  Sonic performance is excellent with a good balance across the frequency spectrum.  With a long 18 hour battery life, USB charging, and subtle LED light, the Q7 is easy to use and great for transport.  Issues include hiss with high sensitivity headphones, IEMs, and CIEMs as well as a slow changing volume control that limits the maximum volume for low volume sources or very low sensitivity headphones.  The Ortofon MHd-Q7 can be a real audio treat when paired with the right gear, and the aesthetics and usability add to the attraction.  

 

 

Manufacturer Model Price Form Factor DAC Power Charge Interference 4 Pin Compatible
Bit Depth Sample Rate
Ortofon MHd-Q7 $398 Portable N/A N/A Battery USB None Yes

 

Quantity Warmth Note Sustainment Smoothness Soundstage
Deep Bass Bass Mid-Bass Midrange Upper Mids Treble Width Depth Imaging
6 5.5 5 5 5 5.5 5 6 8 8 7.5 9

 

Bass Mids Treble Transparency Dynamics Resolution/Detail Clarity Soundstage Score Total - Quality Hiss Imbalance Size/ Portability Total Quality, High sensitivity IEMs
Quality Quality Quality
9 9.5 9 9.5 9.5 10 9.5 8.2 9.1 4.5 9.5 6.0 7.3

 

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Manufacturer: Leckerton
Model: UHA-6S MKII

 

  

 

 


Price: $279
Product notes: Available in black or silver.  Tested with stock AD8610ARZ op amp; OPA209AID, AD797ANZ, and OPA627AP (+$50) also available.
Type: DAC/amp
Volume control: analog
Power connector:micro USB

Battery life: 30 hours for analog input (line in); 10 hours for digital input (USB, optical, coax)
Features:
- High-performance Cirrus Logic DAC. The CS4398, Cirrus Logic’s flagship digital-to-analog converter, is a long-time favorite of audio enthusiasts due to its exceptional performance and audio quality.

- Optical and coaxial S/PDIF digital inputs. The UHA-6S.MKII is compatible with S/PDIF sources up to 24-bit/96kHz.

- True ground audio reference. With bipolar voltage rails at +/-6 VDC, there is no need for an output ground buffer which can cause additional output distortion and other audio artifacts. This also allows the UHA-6S.MKII to be used as a low-noise DAC/preamp into a line input such as an A/V receiver. Additionally, there are no DC-blocking capacitors in the signal path, which can cause harmonic distortion.

- Socketed op-amps. For full customization, the output stage op-amps in the UHA-6S.MKII are socketed and easily replaceable. Single-channel op-amps are used throughout for minimal channel crosstalk.

- Two-position gain control. Optimize performance for your headphones or earphones by choosing from two gain settings.

- Automatic input selection. The input is automatically selected among the four available sources: analog, USB, optical S/PDIF, and coaxial S/PDIF.

- Advanced battery management. Use any high-power USB port or USB charger accessory to charge the UHA-6S.MKII. A rear panel switch disables charging, maximizing the battery life of your portable computer or tablet PC. The front-panel power LED indicates low-battery status. A battery disconnect circuit prevents full discharge, maximizing the lifetime of the battery. The UHA-6S.MKII is compatible with most standard 5V USB wall chargers.

- Plug and Play USB operation. The UHA-6S.MKII uses the standard USB audio drivers which are included in Windows and Mac operating systems.

Works with 4 pin headphone plugs: Yes

Channel Imbalance: Yes, with high sensitivity IEMs at very low volumes. 7/10

Hiss: Slight with high sensitivity IEMs; increases as volume knob is turned up.  9/10
Interference: None

Noise when turned on/off: On = none, off = slight squeak

 

The UHA-6S MKII is an extremely popular amp/DAC that offers a lot of functionality in a small size.  Before this review I heard many good things about the amp with the original op amp configuration of the OP209, as it outperformed many amps in the price range.  Talking with Nick, he recommended reviewing the new standard op amp, the AD8610, which is the configuration tested. 

 

Starting with battery life, the amp will run for 30 hours with a line level analog input and around 10 hours using the DAC/amp.  Using a micro USB connector is a nice touch as pretty much all mainstream devices are going that way.  There are switches on the back to turn the amp/DAC on or off, and a switch that allows the 6S to charge from a connected device or just use the internal battery for DAC functionality.  This is a nice feature if you want to use the 6S with an Android phone as the amp will probably outlast the phone, or if you want to conserve laptop/netbook power. The DAC can be fed from optical or coax as well, and when plugging either of those along with USB, the amp selects either the optical or coax over the USB input, which makes sense.  The amp also offers a high and low gain switch on the front panel.

 

The sound signature of the 6S is overall neutral with an analytical leaning note presentation due to note decay that is on the quicker side of natural.  This accentuates details, but can lead to a harsher sound, especially when there are peaks in the upper frequencies.  Soundstage presentation is accurate in proportion and size wise and competes well within the price range.  Dynamics are about middle of the pack as is transparency while clarity is good in large part due to the note decay.

 

Testing with multiple headphones, IEMs, and CIEMs such as the HD600, K550, HD598, Custom Art Music One, P2+1, IE800, SE5, NT-6 pro, IERM aud-8X, ER4, and more did lead to a mix of synergy levels when compared with other amps.  While most headphones I tested with the UHA sounded good including the LCD-2, IE800, SM64, IERM, two stood out in a bad, the Dream Earz aud-8X and Proguard 2+1, as they were harsh and lacked dynamics.  I compared the 6S primarily with portable amps as I only have one other DAC/amp, and the ODAC + O2 combo equivalent isn’t truly portable.

 

When comparing the Arrow 4G with the 6S, I found the 4G had more variation from headphone to headphone and from source to source than the 6S, but when the synergy was good, the 4G had a higher maximum potential.  The 4G soundstage presentation was larger using better sources such the DX100, but the two performed at more similar levels when the internal 6S DAC was used, and the 6S pulled ahead from an iPhone 4S.  Resolution of the 4G is higher, but it is only apparent when paired with a source that is more resolving than the internal 6S DAC such as the ODAC or DX100.  The overall presentation of the 4G was more refined and smoother and the 4G didn’t have the same synergy issues with the aud-8X or P2+1, but didn’t synergize quite as well with other CIEMs such as the IERM and SM64. The 4G could at times sound warmer with much lower levels of deep bass in comparison with the 6S, but this wasn’t always the case depending on the source/headphone pairing. Both have their own strengths and weaknesses in sound as well as functionality as the 6S provides a DAC while the 4G has adjustable bass and treble as well as crossfeed.

 

While the Just Audio uHA-120 performance was close, it wasn’t as open or resolving as the 6S, but the notes are a bit more organic and smoother leading to an easier listening experience, especially with more analytical headphones.  As with the 4G and 6S, the 120 changes with source and various headphones and performance is about the same with my lower end sources and as the source quality increased as well as the capability of the headphone, the 120 trailed the 6S in dynamics and soundstage size by an increasing margin.  The Pico Slim was more refined, smoother, natural, realistic, and brighter than the 6S, but the PS trailed in dynamics with several harder to drive headphones.

 

The internal DAC of the Leckerton is a 16 bit 48KHz resolution DAC with USB, coax, and optical inputs.  For a direct comparison of the inputs, I used the optical and coax outputs of the USB connected Musiland Monitor 01 US, which improved the sound quality over the 6S USB input by increasing the space, instrument separation, and overall clarity within the presentation.  The amp was capable of performing at higher levels from the coax and optical inputs from the DX100.  While the sound signature of the DAC is well matched with the amp, the overall technical performance of the DAC holds the internal amp back in some ways and the amp hold the DAC performance back in other ways.  This indicates there may be more potential from the 6S with different op amps. 

 

The ODAC was more dynamic and spacious than the internal 6S USB DAC and could push the 6S internal amp to higher performance.   The internal 6S DAC did outperform the HUD-MX1 DAC via USB as well as optical, but the performance difference via optical input was much smaller (although the MX1 uses an upgraded op amp).  Another DAC/amp, the Cruise performed at a higher level than the 6S DAC in dynamics, clarity, and transparency with a smoother treble response even though the Cruise has a fast note attack and decay.  However, the 6S easily beats the Cruise in hiss, size/form factor, and functionality.  The ODAC + O2 combo equivalent provided a more spacious and dynamic yet less resolving sound than the slightly clearer 6S.

 

Note: Talking with 6S owners, the OP209AID and OPA627, but there are drawbacks as mentioned on the Leckerton site.  To quote the Leckerton site: “The AD8610 is currently the best choice for most customers. It measures very well electrically, it has low susceptibility to interference, and it has a proven record in the world of portable hi-fi.

When might you consider the other options? If you’re an experienced listener and have experimented with different op-amps, you may certainly have your favorite. But if you’re not sure or just starting out with hi-fi headphone amps, the AD8610 is the way to go. The AD8610 is currently the best choice for most customers. It measures very well electrically, it has low susceptibility to interference, and it has a proven record in the world of portable hi-fi.

I hope to be able to test the other op amp options in the future.


Summary: There is a lot to like with the UHA-6S MKII from the relatively small size to the computer and Android compatible DAC to the options to the good sound quality and ability to change op amps.  With the stock op amp, which was the only configuration tested, the sound was on the analytical side with good performance considering the complete package provided.  The amp has a low noise floor, no interference, and plenty of volume with some headphones synergizing well while a few others didn’t.  With op amp upgradability, there is still room for improved performance in the amp section.  There are better sounding amps, smaller amps, and amps with more “amp” features, but for the combination of sound, size, and functionality the Leckerton UHA-6S MKII is truly a winner.

 

 

Manufacturer Model Price Form Factor DAC Power Charge Option Function Auto on/off Interference 4 Pin Compatible
Bit Depth Sample Rate
Leckerton UHA-6S MKII $279 Portable N/A N/A Battery USB Micro AD8610ARZ op amp  Amp only No None Yes
16 48K Amp/DAC (USB)
16 48K DAC only (coax input)

 

Quantity Warmth Note Sustainment Smoothness Soundstage
Deep Bass Bass Mid-Bass Midrange Upper Mids Treble Width Depth Imaging
5.5 5 5 5.5 5.5 5 5 5.5 5 7.5 7.5 6
5.5 5 5 5.5 5.5 5 5 6 6 7 5 6
5.5 5 5 5.5 5.5 5 5 6 6 7.5 7 8

 

Bass Mids Treble Transparency Dynamics Resolution/Detail Clarity Soundstage Score Total - Quality Hiss Imbalance Size/ Portability Total Quality, High sensitivity IEMs
Quality Quality Quality
8 8.5 7.5 8 8 8.5 8.5 7.0 7.7 10.0 7.5 7.0 8.0
8 8.5 7.5 7 6.5 8.5 8 6.0 7.3 10.0 7.5 7.0 8.0
9.5 10 8.5 9 8.5 9 9 7.5 8.5        

Edited by average_joe - 7/17/13 at 9:17pm
post #3 of 279

Nice review you have coming along here! just in time because im in the market for a good amp atm aswell!

post #4 of 279
Thread Starter 

Thank you, what is your price range, source, and headphones?

post #5 of 279

I see an excellent thread brewing !

post #6 of 279

 

Quote:
Originally Posted by average_joe View Post

Thank you, what is your price range, source, and headphones?

 

source: ipod nano 3g

headphones: sennheiser HD25-1 ii

budget: $150 tops


Edited by AyeCee - 12/20/11 at 4:00am
post #7 of 279

wow, this looking to be a great thread!

post #8 of 279
Thread Starter 

 

Quote:
Originally Posted by AyeCee View Post

 

source: ipod nano 3g

headphones: sennheiser HD25-1 ii

budget: $150 tops


The HD25 isn't all that difficult to drive so that price range should be OK.  There are some good options and the Neco V2 I have is great for the price.  I will also be testing an Epiphany Acoustics EPH-O2 and a Mini 3, but at the moment I can highly recommend the V2.

 

Quote:
Originally Posted by BleaK View Post

wow, this looking to be a great thread!


Thanks!

post #9 of 279

Never seen the Cruise before - weird form factor.

post #10 of 279
Thread Starter 

I thought so also, but it works as there is no problem as a desktop amp and for use with my iPod it is fine.

post #11 of 279

Looking forward to your thoughts on the uHA-120 - keep up the good work.

post #12 of 279
Thread Starter 

i.Fuzen review completed (the last review in the first post)
 

Quote:
Originally Posted by estreeter View Post

Looking forward to your thoughts on the uHA-120 - keep up the good work.


Thanks, I will be working on it in the near future.

 

post #13 of 279

I missed this thread until now.

 

Is it possible for you to get a loaner of Arrow 3G, 2StepDance or UHA-6S? I would be very interested in knowing what you think of them :)

post #14 of 279
Thread Starter 

 

Quote:
Originally Posted by esanthosh View Post

I missed this thread until now.

 

Is it possible for you to get a loaner of Arrow 3G, 2StepDance or UHA-6S? I would be very interested in knowing what you think of them :)



As time goes, I plan on updating this thread with more amps, but I need to finish these reviews first. 

post #15 of 279

Thanks for creating this review thread.  I'm looking forward to your review on the O2, as I'm trying to decide between a JDS Labs O2 or possibly the 2Stepdance.

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