Power wise, I don't think you'll have an issue with a 7075. I currently use SuperZeros for surround duty and used to have a 7075. It was more than adequate. With all NHT's though, the more power you can supply the better as they are fairly low sensitivity speakers due to their sealed design. I had Classic 3's for a while (fronts and center) and additional headroom seemed to make a difference. I don't recall the looks of the 855, but the 7075 has a pretty compact profile for an amp. I used to have some amps that were older and never noticed the sound 'degrading' due to their age, so I don't think that's a worry. Guess it boils down to appearance and price.