The Lightning-Quick HeadAmp GS-X mk2 Headphone Amplifier Page 2

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Sound Quality
The GS-X mk2 is a straight down the middle, extraordinarily competent, solid-state amp. Flat as a board; lots of juice for the big bass notes and hard-to-drive headphones; with authoritative articulation from bottom to top. It's not lush; or euphonic; or romantic; or any other adjective you might use to describe a tube or single output device single-ended amp.

There is one adjective, however, that often does come up when people describe the amp in conversation: Bright. Many say, too bright. On the other hand, during the Big Sound event Bob Katz felt it was the most articulate and accurate amp in the group—aside from his DIY M3 he brought along—pointing mostly towards it's ability to reproduce treble detail. What's going on here exactly?

I spent most of my time with the GS-X mk2 directly comparing it with the Simaudio MOON Neo 430HA I use as a reference amplifier. Using JRiver's Media Center with the DMG Audio EQuilibrium parametric equalizer, I tested the amps with many headphones but spent most of my time listening carefully to the Sennheiser HD 800 (EQed and not); HD 600; and Audeze LCD-4.

The only significant difference between the sound I heard on the two amps was a more transparent and apparent treble response on the GS-X. With the Sennheiser HD 800 without EQ I really couldn't bare to listen at solid level for too long. I tend to err on the warmer side of things for my listening pleasure, and combining the already too analytical sound of the HD 800 with the remarkably fast GS-X mk2 had me fatigued very quickly. This is an overly bright pairing to me.

But when I EQed the HD 800 the story was significantly different. The MOON, in direct comparison with the GS-X, simply didn't resolve treble information as well. Detail that was clear and readily apparent on the GS-X, was confused...or maybe more reflecting what I experienced, lumped together. It's a little hard to describe, I haven't heard treble error in quite this way before, but it maybe something like the difference between really tight, nuanced bass that delivers both impact and the resolution to hear the organic growl of a tuba, as opposed to a less tight bass response that blooms a bit and somewhat obscures the texture of the notes...only in the treble. It's not that the MOON was rolled-off, it just didn't seem to quite force the driver to respond to every tiny detail like the GS-X did.

I thought this might be an observation specific to the HD 800, so I tried the less resolving HD 600, and quite to my surprise the same thing happened. Then I tried the LDC-4 and found the same thing. I thought I might be fooling myself, and what I was hearing on the GS-X might be additional transient intermodulation distortion drawing my attention to the high notes, but the GS-X outstanding measurements lead me to believe it's probably not a technical error making things sound detailed artificially.

No, the GS-X is just a blazingly fast and powerful amplifier. It cares not what you plug into it, it's just going to drive every little wiggle with authority. The big problem, I think, is that so many headphones have problems in the treble that can irritate, and when you plug these headphones into the GS-X mk2 it's going to light those problems right up. This is not an amplifier to use with tizzy, harsh headphones; you'll drill a hole between your ears if you do.

But! If you've got warm-ish headphones, this amp will breath new life into them. I've rarely heard the HD 600 sound so lively. Veil? Ha! No such thing with the GS-X. I even spent a short time with the overly warm but otherwise technically competent AudioQuest NightHawk paired with the GS-X and it was shockingly good fun. (So much fun I'm going to have another listening session with the NightHawk and GS-X mk2 before I ship it away.)

Someone in a thread commented that no one talks much about the bass response of the GS-X. I did find it a little difficult to focus on the differences in bass response between the MOON and GS-X—the readily apparent difference was in the treble, which distracted from focussing on the bass response. I did come to the conclusion in the end that the GS-X bass response was quite similar to the MOON—authoritative, tight, powerful. But it's also clear to me that it's not the defining characteristic of the GS-X—treble detail retrieval is.

Bottom line: The GS-X mk2 is completely unapologetic about its ability and willingness to deliver astonishingly articulate detail retrieval. And if the headphones, and/or you can't deal with it, tough luck.

I find almost all headphone benefit strongly from proper EQ, and with the GS-X it almost becomes mandatory. I'll note here that while using the GS-X with HD 800 I actually found myself dialing up the top octave a bit from where I had it initially set (about 5dB down), I think because there was so much clarity in that range I could take a bit more. With less articulate amps, errors in that range may be more bothersome.

Minor Listening Notes
The 24 step DACT stepped attenuator worked flawlessly without any ticks, pops, or drop-outs as I stepped through the range. I did find myself occasionally wanting the steps to be a bit finer, however.

The GS-X mk2 is almost always picture with the amp unit on top of the power supply. I did measure the amp in this configuration and it had significantly more power supply noise in the measurements then when I measured the amp separated by a few feet. This is not unusual in the least—I've seen it with virtually all other two-box solutions—and I couldn't hear any difference, but if it were me, I'd place them apart for best listening.

Summary
The HeadAmp GS-X mk2 is, in my opinion, one of the most fairly priced high-end headphone amplifiers of which I'm aware. Build quality, and fit and finish may rarely be equaled, but I doubt ever surpassed. The price/performance ratio is outstanding—and that's something you'll rarely hear from me with high-end gear.

This is a purist amp; you will not get balanced drive unless you have a balanced source. The focus here is performance, not handy features.

Sound quality is ruthlessly articulate. If you've got headphones you consider a bit too bright, don't pair them with this amp, you'll just bring out the worst in your cans. EQ is a must if you'll be using headphones with a lean signature. But if you use EQ or pair the GS-X with warm cans you will be shocked with the detail retrieval and resolution to be found here.

Yes, the HeadAmp GS-X mk2 is heading to the Wall of Fame. As long as you understand its character and are willing to abide by its authoritative nature, this is an end-game amp for audiophiles looking for a transparent window through which to enjoy your music.

Resources
HeadAmp home page and GS-X product page. (HeadAmp site has not yet posted the new GS-X mk2 info.)
Head-Fi discussion thread.
SBAF GS-X mk2 discussion thread.
Maxvla's review of GS-X mk2, ECP Audio Black Diamond, and Schiit Ragnarok.
Head-Fi thread "Kevin Gilmore Amps - Dynalo, Dynamid, Dynahi, Dynamite - Nomenclature explained"
DIY resources for Kevin Gilmore amps of this type.

Measurements

Click on graphs image to download .pdf for closer inspection.

Unlike headphones, I really don't feel qualified to make in depth notes about headphone amplifier measurements. I will say, however, that this is the best measuring amp I've had pass through my lab other then the NwAvGUY O2. A small .pdf booklet with about a dozen amp measurements can be found here.

COMPANY INFO
HeadAmp
200 Douglas Ave #3C
Charlottesville, VA 22902
justin@headamp.com
(434) 981-2829
ARTICLE CONTENTS

COMMENTS
zobel's picture

I'd say this amp is way ahead of the source (recording) and the transducers (cans), and it may remain so for decades. The fact that you recommend EQ on any headphones it powers proves this point. I lust for one. It is also interesting, and encouraging that it also measures so well. My HD600s like my O2, and no doubt they would love this Headamp. This ought to be your reviewer's tool to suss out differences in cans, if it is as fast, precise and uber-clean as you say! This is closer to accurate than the Moon, right?

detlev24's picture

Right. This one is closer to "a wire with gain". A very nice peace of hardware!

My reference choice for headphone evaluation would probably be the SPL Phonitor 2. Loads of power and excellent in neutrality + accuracy; plus some useful features like a good crossfeed. There are not many amplifiers on the market that are build as well as those two mentioned candidates. What a pity...

TMoney's picture

Fantastic review, Tyll. If I wasn't about to take deliver on another amp I'd jump on a GSX in a second.

I noticed that you mentioned you listened to the GSX through the LCD-4s. Is there any chance of seeing your data sheet with the measurements for the LCD-4s a bit early before your usual "end of the month" update?

Tyll Hertsens's picture
I've measured them and they seem to be a bit different, and superior, to the others in the line. I will be reviewing them.
TMoney's picture

Very interesting to hear. Looking over your data sheets for the other Audeze LCDs I've never thought they measured quite as well as I would like.

I'm very much looking forward to hearing/seeing how the new one measures (especially the 300hz sq wave) in light of all the new competition in the planar space. With the HE1000/HEX and Ether performing and measuring as well as they do, I hope Audeze has done something special to remain competitive.

tiger's picture

I have a hunch you will have similar feelings to the JDS Labs Element. Have you ever given it a try, Tyll?

Also, I can't imagine that you haven't played with the new 800S yet (given that you have with the LCD-4). Just keeping them for yourself now?

zeissiez's picture

Great review there, very informative stuff.

But I have to say while the price is competitive but the real bargain is Audio-GD Master 9, at USD1.5k, which beats the Moon 430HA. Here's a comparison Master 9 vs 430HA

http://headmania.org/2015/03/08/simaudio-moon-430ha-headphone-amplifier-...

mat's picture

Another great review. Thanks Tyll.

Quote:

Unlike headphones, I really don't feel qualified to make in depth notes about headphone amplifier measurements. I will say, however, that this is the best measuring amp I've had pass through my lab other then the NwAvGUY O2. A small .pdf booklet with about a dozen amp measurements can be found here.

I'm curious if you have any plans to do a full review of the O2. It seems like a steal for the price and potentially even Wall of Fame worthy if the measurements are any indication. It's significantly cheaper than anything currently on the Wall, so it might be a good addition for anyone on a tighter budget.

Also, that link to the headphone amp measurement PDF booklet seems to be broken.

Harry Manback's picture

If the O2 measures better, then it is better, right?

By definition, an amplifier takes it's input and outputs it at a different volume. Any tonal deviation of output from input is coloration, and thus a flaw. If an amp makes headphones "brighter", then isn't it flawed? (Assuming ALL other amplifiers are not flawed...).

The Federalist's picture

Thanks for the review and the honest word on synergy with the HD800... I don't know that I'd want to lean on digital EQ in order to use a headphone with an amp so will probably continue admiring Head Amp from afar. Although I have other ways of compensating in the analog domain that may make it worth it down the line.

Head Amp has some historical significance to the hobby so I feel like someday I'll need to break down and buy one. A First Watt amp for headphones so to speak.

It seems like using the lowest noise, lowest distortion JFet ever created for the inputs in the 2SK170/ 2SJ74 coupled with a likewise super symmetrical BJT output stage may be the reason the sound is so "clean" on its lonesome.

It'd be interesting to know if the BJT's were swapped out for Mosfets if a dose of sugar ala 2nd order harmonic distortion could be added into the mix.

Still the parts quality, build quality is top shelf.

coldassault's picture

How would the GS-X mk2 compare to the Auralic Taurus Mk2? I'm interested in the EQ test, as that one exposed some weaker points in the 430HA. The Taurus used to be on the wall of fame, and used to be your reference amp, but it was retired for an amp of almost 2 times the price (where the headphone page seems to cater more different price points in this regard to my feeling; applying that same logic, the 430A offers more bang for the buck despite its hefty price increase over the Taurus). So I'm beginning to expect that the Taurus is quite a bit worse actually...

xp9433's picture

I thought your reference HPs were the HE 1000's, so I am surprised they didn't get a mention in this review.

Any commentary you can make of the GS-X Mkii and He 1000's as a pairing would be much appreciated.

rickruss's picture

I too am anxious to hear your thoughts on the pairing of the two.

Mauro's picture

Ciao Tyll,

I understand that you don't feel confident to tell the difference between amps just by looking at graphs, but maybe you could give us an overall view of the single measurement adding an article in the "Measurements Explained" section. I am sure that you are much more knowledgeable that part of the readers.

Chiumeister's picture

Were the unbalanced inputs results as great as the balanced inputs ones?

Chiumeister's picture

Tyll,

Would one of the working HeadRoom Ultra Desktop DAC feed the GSX-MK2 nicely or time to look for a better balanced out DAC. Or in your view, necessary for a balanced out in the first place.

GloryUprising's picture

I've visited Justin's workshop in person to pick up my GS-X Mk2; this was at the height of the delays due to front panels.

I asked to see the 'bad panels' and Justin obliged. The panels at first glance looked 'fine' to me and I stated as such....then Justin showed me a 'good panel' and the good one BLOWS the poor one away. If I didn't have a side by side comparison, I would think it was a trivial matter. But after seeing the such an obvious attention to detail and integrity of such pride I knew Justin was a manufacturer true to his word.

I think Tyll nailed it and Justin is doing right by his brand by insisting on such quality... He could have easily used the 'bad panels' and most would not have known the difference.

GloryUprising's picture

I've visited Justin's workshop in person to pick up my GS-X Mk2; this was at the height of the delays due to front panels.

I asked to see the 'bad panels' and Justin obliged. The panels at first glance looked 'fine' to me and I stated as such....then Justin showed me a 'good panel' and the good one BLOWS the poor one away. If I didn't have a side by side comparison, I would think it was a trivial matter. But after seeing the such an obvious attention to detail and integrity of such pride I knew Justin was a manufacturer true to his word.

I think Tyll nailed it and Justin is doing right by his brand by insisting on such quality... He could have easily used the 'bad panels' and most would not have known the difference.

GloryUprising's picture

Wow. Sorry for the bad grammar. I think you guys get the gist.

System's picture

Tyll

I'm looking for a dac to go along with GS-X MK2/Focal Elear. I was hoping you could give me a recommendation on what would go along well with this amp or at least a couple of suggestions.

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