I'm really surprised this amp hasn't gotten more attention. I've had it for about a month now, and I'm extremely happy. I'm using Audeze LCD-24 (which really shines when you give it a lot of voltage even though you wouldn't think so based on the specs), the LCD-2, and Focal Clears. (My source is a Chord Qutest DAC)
A few things I've noticed. First, unless your headphones are super high sensitivity, don't use the low gain mode on the back. Keeping it in high gain mode, even with the volume lower, significantly increases the width and depth of the soundstage on my unit. (I know you don't get to see as much of the VU meters that way, but who cares I'm more interested in the sound.) The amp is very transparent, very neutral and fast sounding. With the Qutest and the lcd-24's, I get a great punch to the bass but with fantastic detail.
I did some tube rolling experimentation as well. I happen to have a bunch of NOS 12AU7 tubes from some of my previous tube amps. I'll be honest, most of them are a small difference depending on preference, until we come to the 6350 tube. You will need a 6350 to 12au7 sock adapter for it (the only difference is the pins that correspond to the grid and plate of each triode are reversed from the 12AU7 connections.) They were developed for IBM and other computer companies, and I find them to be a significant upgrade. My personal favorites are the RCA (little warmer) or the GE (more analytical). (I hear the Sylvania ones are also nice but I do not own one so I can't compare.) The difference in soundstage, depth, bottom end and top end extension when I put in the 6350 in place of the 12zu7 (or ecc82 as it's named in EU) is quite significant.
I do not suggest changing out the power tubes. I did try, and I found that speed that I really like is this amp is gone when you change the 4 power tubes.
Unit gets a bit warm by the tubes, but not any more or less than any other tube amps I've used. Funny addition, I've seen some people not getting remotes with the unit, for some reason mine had two in the box!
Lastly, I contacted their support before I changed tubes to get a little more info, and they got back to me very quickly, were extremely friendly. I'm VERY happy with this purchase. Don't sleep on this amp, it's great. Amp on high gain, even with volume at 9-10 o'clock, 6350 tube in pre section (V1 socket), and I've been in sonic heaven since I got it.