Gustard H20 Headphone Amplifier with Sparkos Labs Discrete Op Amps. By Soumya Banerjee Indian Audiophile Forum

It's been a while (about 2 months) that I have had the Gustard H20. I was one of the first to pull the trigger on this headphone amp which was so little talked about. Lack of reviews in common circles was holding back my purchase decision. Yet both by specs and depicted data on Shenzhen and AliExpress, I had a feeling this amp would sound phenomenally great with a myriad of loads.

H20 supersedes Gustard's previous offering H10 which heavily borrowed designs from Violectric V200. The amp was well received in Head-Fi and elsewhere, partly because it does sound great, and partly because it allows OPAMPs to be swapped. One of the things I liked about H20 was that the OPAMPs are still DIP-8 packaged and swappable. The stock configuration uses 2 x LME49720 dual op amps.
Gustard H20 headphone amp
Upgrade/Mod with Sparkos Labs SS3602 Dual Op amps: You would be inclined to think, given an excellent stock op amp like 49720, how could one possibly do better than the H20 stock sound. Well the key lies in using a discrete op amp instead of another run of the mill IC.

I took out the 49720 op amps out of the H20, and put in the SS3602s. I didn't put the top cover on it yet - just in case the mod goes downhill and I happen to prefer 49720's. Except that never happened. While my H20 remained topless for the next 7 hours or so, it didn't take me long to conclude that 49720s are not going back in; that this is not some subtle change in tonality or some more layering and articulation over stock configuration. Yes there were all of those - but just like A5 one thing that stood out was details because of high SNR. It's weird on specs both 49720 and Sparkos have similar SNRs, yet SS3602 tests the resolution limits of your DAC. And yet the sheer amount of details, those laser etched sharp transients and tone separation were breath taking.
SS3602 audio upgrade in Gustard H20
SS3602 is seemingly devoid of coloration. It will instantly make you realize that the 49720 op amp had a warmth in the mid (in a very pleasing way albeit). You will know what neutral tonality is when you listen to these. Neither do they emulate any artificial soundstage. Like 49720, it does not have a defined boundary for a soundstage as such, yet if the source material has such spatial information, it portrays them with immense accuracy. The biggest change with Sparkos SS3602 is the portrayal of height and depth as it conveys exceptional information about the recording environment - which was very evident on tracks from A. R. Rahman. Was listening to Sissel - Lær meg å kjenne. Gosh those smacking of lips, her breath, that intro passage of otherwise indistinct radio chatter - was so vividly portrayed by Sparkos.

Make no mistake 49720 is a very good part in itself, but coming from that to SS3602 will make you realize 49720's transients get smeared with each other. Yes, that's how sharp transients are with ESS 9028 and SS3602!
Hi Fi op amp discrete Gustard H20

Needless to say because of the insane detail retrieval, the layering even from average tracks is nothing short of breath taking. I could listen to even the most hideous tracks in my playlist having on my Kaiser Encore and Gustard H20 - just because I so love chasing those hidden sonic details and layering effects. To give an idea Stine Grove's vocals in Tears (Acoustic Piano mix) lingers so long along side the piano playing. Or for that matter how I can make the studio arrangement of the instruments in Vanessa Mae's Sabre Dance - specially the transition from mono like sound to sudden 3D like effect.

Extension on the Sparkos SS3602 is nothing short of stellar. The low end really approaches DC limits. It's been few days now, and yet I can't keep drooling over low end rumble and wobble the amp imparts to my headphones and IEMs after this upgrade.

Gustard H20 upgraded with SS3602 discrete opa

Because of such insane details, one has to be mindful of 'side-effects'. Until the Sparkos op amps arrived I used to have my M8A DAC PCM re-sampling filters set at Linear Phase slow roll off. It's not easy or at least it's not something that jumps right at you when you switch PCM re-sampling filters of a DAC, and I used to listen to several tracks for a while and decided slow roll off sounded clearer and less aggressive. However with SS3602, I was surprised how effortlessly it lets you listen to differences in PCM re-sampling filters. That pre-ringing in Linear Phase is so evident regardless of whether it's slow or fast roll off; it just makes the transients sound congested. Minimum phase is what I settled on, and it sounds absolutely sparkling clean! I guess pre-ringing is indeed a greater evil than post-ringing.

Closing notes for Sparkos SS3602, I am pleasantly surprised by how much of an upgrade this is rather than a tiny improvement in my Gustard H20. If you got a high end DAC/Amp which allows for rolling op amps, take my word for it, get these. This will be least intrusive 'upgrade' you can do to your gear. Though do check with Andrew first if the part is a right fit for the gear and the stage.

As for the Gustard H20 itself, I'm yet to run into a better sounding and more versatile desktop amp at this price point. It's definitely many leagues above my previous amps like Schiit Lyr 2 and Valhalla 2 in just about every department. And the sound quality alone justifies the price point - provided you have good enough transducers to take advantage of it.

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