Vali is great sounding, but it has some ringing when you put in the cable or hit the table with something. It never bothered me, and I had one of the earlier model (first 200 or so) which they said had even more ringing. I still have the amp, and plug it in sometimes for AB-ing something or listening next to the bedside. IMO the greatest price/perfomance-ratio amp for the HD800, with the downside of some ringing. Which again, never bothered me.