Disclaimer:
 
I’m somewhat of an enthusiast at this point in the game. I don’t consider myself an audiophile yet by any means. I feel someone that is a true audiophile seeks the purist, most untainted reproduction of sound and is always tweaking and striving to better their gear. Because I don’t have the ultimate means or the hardily trained ears to be an audiophile, I’ll leave that title to others better and more experienced than I. What I do believe is that music is the #1 priority always and forever. As an enthusiast, my goal is to find gear that is enjoyable to me regardless of how accurate and/or well measured it is. Measurements are incredibly useful for both assessment and for purchasing, but I let me ears and brain decide if I like what I’m hearing or not.
 
With that said, my preferences have changed over time as my ears “mature”. I used to love strong, emphasized bass (not basshead bass) with a strong mid presence that is lush and warm. Detail retrieval, imaging, soundstage, dynamics… all of those things were like foreign language to me. They weren’t very important. As I’ve climbed the ranks, upgraded my gear, and started to critically listen to my music, my appreciation for the technical aspects of music reproduction have blossomed. I now have a need for excellence in all of those aforementioned areas. I’ve since partially grown out of that phase and into what I feel is my preferred sound. I enjoy something that is natural and realistic. I still love hard-hitting, accurate bass but not overly so. I know those are subjective terms, but as a closet musician, I feel I have a firm grasp on what Piano, Drums, Bass, and Guitar sound like in real life. Those sounds need to be as real as if I were playing them in order for me to want to keep something.  Overall I prefer a neutral tonality, with slight warmth. A sound that is non-fatiguing, with plenty of air and space between instruments - deep and appropriately wide soundstage, with excellent spatial cues and imaging. Last but not least, a large dynamic range. Those factors and criteria are tested every time I evaluate my gear. If they pass most or all of those subjective tests – they stay, if not they go (most of the time). 
 
Test Equipment:
 

1. Source: C.A.P.S. Carbon v3 (w/ Paul Hynes PSU)
2. Software: JRiver 19 (ASIO)
3. DACs: MSB The Analog DAC / AMR DP-777
4. Amplification: Audio GD Master 9 / HeadAmp GS-X mk2 / Rogue Audio Apollo Monoblocks (for Preamp testing)
5. Headphones: HD800 / LCD-X / HE-6 / Mad Dog / TH-600 / TH-900’
6. Speakers: Tekton Designs Pendragon

 
Technical Specifications:
 
HeadAmp GS-X mk2: Pure Class A – Solid State Headphone Amplifier / Preamp 
 

1. Frequency Response: 5Hz-50KHz (+/-0.1dB)

1. Signal-to-Noise Ratio: >100dB

1. Total Harmonic Distortion: <0.006%

1. Gain: 1x / 0db, 3x / 9dB, 8x / 18dB

1. Output Impedance: less than 1 ohm

1. Output Power: 1 W (SE), 2 W (Balanced)

1. Inputs: 1 XLR / 1 RCA

1. Outputs: 2 - Combo Jacks (¼” and 3-Pin XLR) / 1 - XLR / 1 - XLR loop-out / 1 RCA loop-out

1. Preamp Outputs: 1 – XLR / 1 – RCA

1. Chassis: 14.5" (length) x 9" (width) x 5" (height)

1. Weight: 12 lb

 
Audio GD Master 9: Pure Class A - Solid State Headphone Amplifier / Preamp
 

1. Frequency Response (XLR): 20Hz – 20KHz (+/- 0dB)
2. Signal-to-Noise Ratio: >130dB (Input short, XLR mode)
3. Total Harmonic Distortion: <0.002%
4. Gain: Low Gain - +14dB (XLR) / High Gain - +20dB (XLR)
5. Output Impedance: 1 ohm
6. Output Power (Balanced): 9 W @ 40 ohm / 3.8 W @ 100 ohm / 1.25 W @ 300 ohm / .63 W @ 600 ohm
7. Output Power (Single-End): 2.5 W @ 40 ohm / 1.05 W @ 100 ohm / .35 W @ 300 ohm / .175 W @ 600 ohm
8. Preamp Output Level (Max): 10V @ RCA / 20V @ XLR / 4.8MA @ ACSS
9. Inputs:  2 – XLR / 2 – RCA / 1 – ACSS
10. Outputs: 1 – 4-Pin XLR / 1 – 3-Pin XLR / 1 – ¼”  
11. Preamp Outputs: 1 – XLR | 1 – RCA
12. Chassis: 17” (length) x 17 (width) x 3.6” (height)
13. Weight: 

 
The Sound:
 
Out of the box, the M9 sounded very good. It seems Kingwa breaks-in each individual product for 300 hours or so before sending it off. I didn’t find my difference in my initial 100 hours, although some treble smoothness – and some effects of definition in the bass were noticeable. Other than that, the M9 is ready to go as soon as you set it up.
 
M9: Overall is slightly warm but not overly so. Initially I thought this amp was going to be brutally honest, being the most neutral amp I’d had ever heard, but I just don’t find that to be the case. It has great non-offensive sound that has excellent synergy with both my HE-6 and HD800. Bass is tight with great texture and weight. Impact and slam could be better, but that could be my DAC, which I find to be slightly rounded in the lower regions. Mids are clean and clear without a hint of grain. A non-fatiguing response that is extremely enjoyable with everything I’ve thrown at it. The treble is definitely my favorite aspect of this amp. It has great extension and clarity while only exhibiting a small bit of sibilance with poor recordings. It has a smoothness that isn’t present in comparison to the GS-X mk2. This could come down to personal preference, but in terms of overall transparency I find the M9 to be more accurate compared to the GS-X mk2. 
 
     
 
GS-X mk2:  In comparison more neutral although with some slight emphasis in the bass region. Bass is extremely tight, controlled and extended. This is where I find the GS-X mk2 to shine - the way it can grab a headphone by its virtual balls and control the hell out of sloppy bass, overly bloomy bass and even refine good bass. It won’t transform overly bassy headphones into well textured and refined beasts, but it will clean up and control bass to a point where you won’t recognize the sound even though you are listening to the same headphone. Mids are crystal clear, clean and up front (not as laid-back as the M9). You could say the GS-X mk2 has a more aggressive tone. Treble is where things get a little hairy. One of my few complaints about the GS-X mk2 is the treble response. I feel there was always something about the treble that was slightly unnatural. It is hard to describe, but I feel there is some etch, glare that I hear with certain tracks. It wasn’t apparent on everything I listen to, but on some tracks it was there – and it could become fatiguing especially with an ultra-revealing phone like the HD800. This is me nit-picking, and I’m sure there are plenty of people that won’t agree, but it was one of the few problems I had with the GS-X mk2. Overall a very small price to pay considering how versatile and well rounded the amp is. 
 
        
 
Imaging on the M9 has good precision. I was able to accurately pin-point instruments and vocals very easily. Soundstage is appropriately deep, but could stand a bit more width. In comparison, the GS-X mk2 has a more expansive, 3D staging giving the impression of more air between instruments. Detail retrieval is also very good, albeit not as good as the GS-X mk2. The GS-X mk2 is faster and more transparent. Everything sounds airier, better separated on the GS-X mk2 regardless of what headphone I used. Dynamics are also better on the GS-X mk2, although this is a closer race, and one could easily prefer the M9 in terms of dynamics over the GS-X mk2. Overall I find the M9 to be slight less proficient in the technical aspects in comparison to the GS-X mk2. Both are very good, and definitely make my top 5 SS amps I’ve ever heard in terms of staging, imaging, separation, and dynamics.
 
 
Headphone Pairings:
 
I wanted to include this section because I’ve been asked several times whether or not the M9 has the grunt and finesse to power the HE-6. I’ve also been asked if the HD800 has good synergy as well. There is always a reluctancy in the back of mind when I order something new with very little information in form of reviews, impressions, etc. on how it does with the wide range of headphones that pass through my house. I’m always trying new headphones, typically not with the idea to keep but just out of curiosity - how it sounds and how it compares. I’ve finally found my trifecta with the HD800, LCD-3, and HE-6. Owning these three headphones give me the range and covers all my bases. I can switch headphones depending on mood and have the versatility to compare new gear when I’m not feeling lazy. The problem becomes amp synergy and requirements. I feel all three of these headphones have different requirements when it comes to amplification. Buying something that pairs well with all three is a difficult task. I was hoping the M9 was able to at least sound decent with all three and to my surprise it does and then some.
 
HE-6: This pairing was the most important, and the largest risk to me. We all know the myths and exatrations that pass through these forums regarding the HE-6 - they NEED 100wpc to sound their best – blah blah. Well I don’t buy into that crap, but I do believe the HE-6 are power hungry and need lots of grunt. At the same time they need clean power that packs a ton of punch but has the finesse to soften the semi-hard treble and get rid of the etch. Well, the M9 definitely delivers. Sound signatures match up very well having good synergy, and there is plenty of headroom on the volume pot. Out of the 100 steps – I’m at 60. Over the years, I’ve come to find out that I listen to music relatively loud. Any sane person shouldn’t listen at 60 unless they want to jam all day err day like I do. The M9 DRIVES the HE-6 with authority, and I can’t say it gets a lot better. For a headphone amp, the M9 does a surprisingly good job.
 

 
HD800: Even after hearing the GS-X mk2 and M9 with the HD800, I still feel the HD800 belongs with tubes. I can’t get over the bright treble and the artificial staging the HD800 has without the realism tubes bring along. There aren’t very many SS amps/HD800 combos that my ears agree with but the M9 comes really close to be the best. It does smooth out the treble, and give me the warmth I need for the HD800 to sound somewhat natural, but there are still some missing pieces that I have yet to find in any SS combination. The upside is you get a very nice bass response with the HD800, adding a bit longer decay which in turn makes the sound more engaging. The HD800 is an uptight prude, but with the M9 – it shows some skin. Overall I like the pairing. I could definitely live with it, tweaking other things in my chain like full copper interconnects, and a warm/slightly laid-back DAC.
 
    
 
LCD-3: TBD – My LCD-3 are out right now, only had a few days (few hours really) with it before they were sent out, but will update this post when I get them back.
 
Alpha Dog: TBD – Waiting patiently on the upgrade list!
 
    
 
Mad Dog: The MD pairing was not to my liking. This was the only headphone that I’ve tried so far with the M9 that I feel sounded better with other amps, even from my DAP (Sony NW-ZX1). After sometime with the MD, I appreciate how good the headphone sounds for the money – but after you hear headphones like the HE-6 etc. the pairing just didn’t jive. Mids were too upfront resulting in shouty vocals, too much mid-bass emphasis clouding lower-end definition and detail, and treble was not crisp and clean. This could very well be the headphone alone, but I just didn’t enjoy the glossy sound between the M9+MD.  
 

 
LCD-X: This pairing was extremely enjoyable, second only to the HE-6 pairing. Sound was very musical and toe-tapping with excellent tightness in the bass and crystal clear treble. Mids were accurate and silky smooth. Soundstage did deepen and separation did become more distinguishable. Overall very nice, non-fatiguing sound.
 
Sidebar - Really liked the LCD-X headphone as a whole. I feel the this next gen Audeze line is truly on to something, and I look forward to what the LCD-4 brings. The difference in sound wasn’t enough to justify owning it, or selling my precious LCD-3 off  but I can appreciate good engineering and this is definitely one of the best headphones I’ve heard.
 
TH-600/900: These two headphones need bass control. I don’t feel these headphones sounded their best with the M9 but good enough to still recommend the pairing. The GS-X mk2 is still my reference amp with the TH-900, but this amp doesn’t fall too far behind. Nothing sounded out of place, but the bass could be better controlled and tighter. One of the reasons I have no sold both of these headphones is because the bass can be somewhat overpowering with certain genres. Still feel the treble on the TH-900 is one of best I’ve ever heard, and that wasn’t any different on the M9.
 
    
 
Conclusion:
 
While I find the M9 to be warmer than the GS-X mk2, it still remains quite precise and accurate with great detail and resolution. In comparison the M9 is more full-bodied to the “thinner” sounding GS-X mk2. Depending on the person, these qualities can be seen as coloration and in result a duller sound, but I don’t find that to be the case. The GS-X mk2 is brutally honest, almost to the point of being “raw”. Your audio chain better be up to snuff, from source material to interconnects/power cables. Between the two – I find the overall differences in sound to be more natural and live performance like versus deadly accurate, monitor like sound.  (Natural vs. Neutral?)
 
I don’t want to fill this review with a bunch of superlatives and hype because I’m very much against such writing. What I want to do is convey as accurate as I can what I hear and why I feel this amp is very good in its own way compared to what I’ve heard and specifically the GS-X mk2. The short answer is the Audio GD M9 is the complete package - a very versatile, well rounded headphone amp that can power any and every headphone on the market. The volume control and preamp both are above par, and well implemented.  It has tons of functionality including multiple outs, ins, ACSS, gain settings, and of course a preamp for people wanting their headphone amp to pull down double-duty.
 
Note: Stratus thoughts coming soon, as well as more pictures and more thoughts.
 
Thanks for reading!

[size=12pt]Presentation and Packaging[/size]
[size=12pt]I've been a long time admirer of Justin over at HeadAmp for quite sometime. I've loved his products in the past, but never have owned one. Well this was my chance to finally step into the world of high class sound from HeadAmp. I was very excited to open the box with my Pico Power nestled inside. The box was so small, but was a nice touch. The amp was well packed with foam inserts perfectly cut-out to insure safe delivery of a rather expensive portable amp. To my surprise, there wasn't much in the packaging. Many companies provide what I call "fluff". Sometimes those things are useful, but typically not needed and end up being thrown in a drawer and never seen again. The Pico Power was already slipped into its luxurious case that is made from soft, buttery leather. It has "Pico" embossed on one side, and the HeadAmp logo embossed on the other. Overall a very nice case, that fits like a glove and protects the amp very well. Other than the case, the package includes: A large card that shows the features, information about the batteries used, and his warranty policy for the amp, and a set of flat-head screw caps to replace the set already installed on the amp, in case they are damaged or break. That is it. No fluff, no coupons, nothing but pure basics. [/size]
 
[size=12pt]Just a few notes about the process of purchasing a select few of Justin's amps (Pico Power included). Be prepared for a long wait. Justin's products are very well made, almost to the point of being custom made, so the wait will bother some. His products are very well respected, and are a fine example of small company that competes with the best there is to offer. I personally didn't have a problem waiting a few months for my amp to be ready to ship, but some people will find the wait time to be unbearable, so please take warning on that. Also note that the Pico Power is "In Stock" now (July 8, 2013) at Justin's website - www.headamp.com. The initial batch of Pico Power's were sold out in a matter of days. It seems as though Justin may continue to keep the Pico Power in stock so that wait time will not be an issue. If that is the case, no worries and I'm very jealous. [/size]
 
   
 
[size=12pt]Build Quality and Form Factor[/size]
 
[size=12pt]What is there to say? If you know anything about Justin's amps, it is that they are made with the highest quality materials and assembled by hand to insure top quality control. I would consider his company boutique and it is run like one. The full enclosure (including the battery cover) is made from precision machined aluminium and is anodized to look and feel sleek and smooth. The quality is truly top notch and I can't say that I have every felt something built better in regards to portable devices. The amp is offered in a variety of colors that include: Black, Silver, Grey, Red, Orange, Blue, and Purple. I choose the Black color options just because that is the way I roll, but I have seen the Purple variation and it is simply stunning. The volume pot is also well built, and very smooth. The knob could be a tad larger for bigger hands, but it is acceptable for a portable device. I can understand why Justin choose this size of knob so that it would not protrude much for risk of damage. The jacks (3.5 input, headphone output) are both secure and don't wiggle at all. I have experienced other headphone outs that wiggle a bit and don't securely grip the jack, but that is not the case with the Pico Power. The On switch and the selectable gain switch both have good resistance to them and don't feel cheap at all. They don't seem like the type of switches that will break after a year of use (I'm looking at you ALO). The LED light indicator is not too bright, nor too dim, it is just right. I've found that is shares very similar lumination to the Headstage Arrow 4G. Overall the quality of this amp is without a doubt the best I've ever had the privilege of owning. Has the same, high quality feeling as Justin's desktop amps, and that is saying a lot in the portable world. [/size]
 
[size=12pt]When I first ordered the Pico Power, I was expecting this large enclosure similar to some of the RSA offerings or even as big as the Lisa 3. To my pleasant surprise the Pico Power has a very humble footprint measuring smaller in size than the FiiO E12. It is a tad thicker, but the dimensions are actually smaller. In the features, Justin states that the Pico Power might be the smallest 2x9V amp there is. It is no bigger than an iPod Classic, and is only 0.1" thicker than the actual 9V batteries. A very hard thing to pull off, but Justin has passed the test with flying colors. [/size]
 
[size=12pt]The actual dimensions of the Pico Power are: 4 3/8" (L) x 2 1/4" (W) x 3/4" (H). [/size]
 
     
 
[size=12pt]Size Comparisons [/size][size=12pt](more to come) - [/size]
 
    
 
[size=12pt]Sound Quality[/size]
 
[size=12pt]So the question at hand is how does it sound? How does your other gear sound? Because that is how the Pico Power will sound. The Pico Power is as neutral as it’s going to get.[/size]
 
[size=12pt]The first question that I like to start off with is: What sets the Pico Power apart from its competitors? Well, there isn't one answer to that question, but for the sake of my review... I would say it would have to be the Pico Power's unmatchable way of presenting music. This amp is truly wire with gain. Similar to many of Justin's other amps, the Pico Power is simply the most neutral presentation I have heard from any portable amp (I've heard quite a few - and have owned a fair amount). The first time I turned on my Pico Power, it was plugged into my iPod Touch 4G + CLAS and wow was the sound magical. I was getting no coloration what so ever. Off first impressions, I couldn’t characterize the Pico Power because it didn’t have any characteristics. Whatever your gear sounds like, is exactly what you are going to hear. The Pico Power builds on what is there, and makes it that much more refined. The bass has more control. The notes have more weight and the treble is very detailed. Using my Tralucent 1plus2 IEMs, the sound was just specatuclar. I was using my 1plus2’s with my AK120 alone, but after hearing the Pico coupled it is hard to go back. Every aspect of the 1plus2’s that I enjoyed so much was enhanced and taken up a notch. One thing I should mention is that the Pico Power is very revealing. Because of its nautral ability to represent music with supreme neutrality, it can sound incredible or like glass shattering depending on your source. You can’t expect this amp to mask or somehow make the sound quality better if you don’t feed it quality. But if you do, the sound is truly among the top in the portable amplifier world.[/size]
 
[size=12pt]The sound was simply better than some desktop amps I've heard. At the time, I had a modest setup at my work desk which included a Matrix M-Stage, coupled with my Asus Xonar Essence STX sound card running as the DAC. This setup brought me great sound quality while on the cheap, and was sufficient enough to power my Mrspeakers Mad Dog headphones. When I replaced my M-Stage with the Pico, to my surprise the sound was actually better. The definition and body of the songs sounded more full and the low end was something else. One of the greatest sound features of the Pico Power is the way it renders bass. It doesn't emphasize any part of the spectrum, but improves on the existing sound with more weight and body. The bass reached low, and has great punch with the Mad Dogs. The vocal were liquid smooth with no sign of harshness or sibilance. The treble was very refined and well extended. The amp simply represents your source and headphones the way they were meant to sound. If I could compare the tonality and sound signature of the Pico Power it would be very similar to the GS-1 desktop amp. They sound very similar, but the difference is you can travel and be on-the-go with this! Never did I expect such a small package like the Pico Power to match desktop quality sound, but I'm glad I gave it a shot because this amp truly is remarkable.[/size]
 
[size=12pt]The Pico Power's price tag is quite high, so I decided to give the little guy something that matched it in regards to prestige. Recently I had the opportunity to compare two different setups using the Pico Power as the common denominator. For my first setup up the components consisted of: IPC 7G 160GB (Rockboxed) + Whiplash Audio Custom Twag v2 LOD + VentureCraft Go-Dap DD Socket 1 "Limited Edition" 12V (w/ opamp MUSES02) + BTG Audio SPC Micro Mini to Min + Tralucent 1plus2 (w/ Uber Cable). My second setup consisted of: AK120 (Stock 1.0 FW) + ForzaAudioWorks Claire ICS Mini to Mini + Tralucent 1plus2 (w/ Uber Cable). What an adventure. I still consider myself a young gun to the more experienced folks in this community, as well as a hardcore headphone enthusiast but these two portable setups simply stunned me. I couldn't believe what I was hearing. Never in my wildess dreams did I think a portable setup could match the likes of some of my desktop setups. Well, they did. They still have a few notches to go to match my main setup, but the ability to be portable/transportable (i.e battery powered, durable, and small) this amp really did impress. Each setup had a different flavor, but my preferred portable setup for on-the-go is a slightly warm neutral presentation that is never harsh are sharp in the treble, while maintaining good extension and smooth treble. Overall I preferred the AK120 + Pico Power, but the VentureCraft setup actually did better with my full-sized cans. I would assume it has to do with the fact that the AK120 doesn't have a true line out, but that is just speculation. [/size]
 
[size=12pt]Final Thoughts[/size]
 
[size=12pt]Overall you are getting one heck of an amp, not limiting to just portable amps, if you are considering the Pico Power. It has tons of power to drive headphones such as the Beyerdynamic T1, LCD-2, HE-500, or HD800. It can perform very well against moderately price desktop amps such as the M-Stage, D100, HA-160, just to name a few I've heard and can attest to. It has a small foot print considering its power output and perfectly stacks with DAPs such as the iPod Classic, Touch, and AK120. If you are looking for a portable amp that has a neutral presentation, and doesn't color your music than the Pico Power might be for you. It takes what you hear and improves upon it in all departments. Simply an amazing product that I'm happy I took the dive on. Is it worth the price? For me it was, but for some that believe value is #1 priority might think this amp is a bit too expensive. Let me tell you, that you won’t want to try another portable amp. It meets all expectations for me, and has very few flaws (I’m being highly nitpicky here). If you can get past its battery-only configuration, the somewhat cluttered in’s and out’s, and the cost then everything else will not disappoint. [/size]