My V281 FE has arrived and I got to play with it for a few hours last night. I have the Chord Qutest hooked up via RCA using the Qutest's 3V output, which I think is around 12dB into the V281 and the Topping D70 (original model) hooked up via XLR.
So far I have set the V281 pre-gain to -6dB with my easiest to drive headphones being the Denon D9200 and the hardest to drive being the Hifiman Sundara. I think I could even go to -12dB pre-gain to accommodate a bit more volume range for the very sensitive Denons and I might try that this weekend.
I also have the Focal Clear, Hifiman Ananda & HD650 so there is plenty to try. I use balanced cables on all my headphones.
The difference so far between the Qutest and the D70 is very obvious, with each contributing it's own particular advantages depending on the type of music and the particular headphone used. I also have the Bifrost 2 that I tried briefly but I think I'll leave that in my main speaker setup for now.
I won't comment too much yet on overall performance and sound impressions as it's way too early, other than so far so good
Oh, and I love the industrial look of this amp. It's a beast and I'm expecting some "what the hell is that?" comments when I have visitors.