Do you find the U 280 musically engaging, immersive in the music experience , non fatiguing ?. Aavik claim their low and mid tiers DACs to be warm , musical with good soundstage. Would you agree given your own experience with the U 280 DAC section?
The U-280 is the first amp where I don't miss tubes in my system. I have always loved tubes and owned several tube integrated amplifier (Audio Research GSi75, VAC 160, Audio Hungary Qualiton a50i, Rogue, Raven, and a few more). I also tried SS amps a few times, with the more recent ones being Luxman 590AXII, Naim Supernait3, etc.. But I always went back to tubes. The U-280 is the only amp where I don't miss the familiar tube sound. I feel that it takes the best of both worlds and creates its own unique sound signature.
I can't really say how the D-280 sounds by itself since I haven't tried it, but the U-280 combo is definitely very musical and has a warmth which I never expected to find in a class D amp to be honest. I was actually very skeptical and planned to return the amp to my dealer after a few days of auditioning. But please keep in mind that, despite the warmth, it's not lush sounding like many tube amplifiers. It takes the holographic imaging, the dense cut-with-a-knife palpability of tubes and marries it with the resolution and bass response of a very good SS amp. But it does not masquerade as a tube amp by any means. If someone wants the lushness of tubes then they're better off with tubes. The Aavik focuses more on the purity of sound and lets you peer into the music and present every bit of detail albeit in a very layered, smooth and non-fatiguing way. Last night I listened for 4 hours straight and had to force myself to turn it off so I could get some sleep. So, no I don't find it fatiguing at all.
Hope this helps. Good luck in your search :)