just posting some impressions / thoughts of a pretty stressful week, I own a HD800S and have been using it for a while with just the RME ADI-2 DAC, which imo is a wonderful little combination on its own, however upgraditis struck me recently to go back to balanced.
I heard a lot of great things about the Cayin iHA-6, a very well priced amplifier at 699 euro, I decided to just take the plunge and buy it. few days later the amp arrived in my home, I connect the amp balanced to my RME ADI-2 DAC, plug my HD800S into the 4pin XLR, first impressions were not bad, but not great either, soundstage seemed a little less wide, kinda presented like a "ball of sound" rather than the usual very wide staging of the HD800S on my RME ADI-2, the Cayin generally sounded a little more closed in, surprisingly the vocals were a little warmer than my RME ADI-2 but the treble had a bit of an edge to it at the same time, I listened to the amp for a few hours, went to bed, woke up, started listening a little again, and suddenly the amp developed a horrible screechy high pitched noise, that would change its tone depending on if I touched the cable on my HD800S or not, and depending on volume. Immediately contacted Cayin about this, now I should mention that with the amp sitting on "high gain" my HD800S had a slight background noise aswell, kind of like a windy sound, not really noticeable when listening to music, but still kind of bothered me.
Cayin immediately replied to my e-mails and told me that I can send the amplifier back and get a replacement (amazing customer service), so I did that, and after a day orso I was thinking of how I used to have a Violectric V281 and I kind of missed the amp, I sold it at the time because of personal reasons, financial reasons and kind of being done with the hobby (always chasing the next upgrade), I remember the amp was always quiet no matter what I plugged into it, and the kinda neutral signature with the slight "touch of warmth" was always pleasing to my ears. So anyways I decided to ask Cayin for a refund instead of a replacement, and I had my mind set on getting a Violectric V280 this time, to pair with the RME and the HD800S in balanced.
I managed to get a great deal on a demo model that is pretty much in mint condition. Next day the V280 arrives, I plug everything in, obviously very excited to listen to it, after about a hour orso I was horribly fatigued, the HD800S sounded super bright, mids were shouty and just generally forward, everything sounded way too dynamic. Felt awful for another hour orso, not really understanding why everything sounded so bad, returned to my RME ADI-2 DAC and just using its amp, and everything sounded quite nice and pleasant again, super disappointed with the V280, not really knowing what was going on, so I contact the dealer saying I want to refund it, basically just had enough of constantly being disappointed, the iHA-6 pretty much came DOA and sounded good but wasn't particularly impressive, V280 sounded horribly sharp and mid-forward. Now my dealer just said I could return it, no problem, I already packed everything up again, now about an hour later I get an e-mail from him asking if I have my RME connected via balanced to the V280, which is exactly what I was doing, he told me to try an unbalanced connection.
at first I didn't really think it would make a difference, kinda hesitant to open the box again and go through the process of setting up it after all the disappointment, I eventually decided to try it, plugged in the RCA's, volume was immediately quite a bit less than through the balanced connections, but the brightness / shouty mids were completely gone. the same dynamics were present, the V280 hits pretty hard, bass is very tight, everything just sounded really good. Incredibly happy now, I however saw someone in this thread saying the RME ADI-2 DAC in combination with the V281 / HD800S sounded bright and unpleasant aswell, try switching to just regular RCA's and see what happens. anyways super long post, sorry guys, just happy everything is resolved now, and the V280 is an excellent amplifier, and a great pairing with the RME ADI-2 DAC and the HD800S.