Pl advise on Amp for listening to AOR on Klipsch RF7 Mk II via a custom built R2R NOS DAC

Many thanks to you all for kindly guiding me. At the moment, I have three amplifiers viz. Concept 16.5, Krell KAV 250a and NAD C326BEE. All three amps provide decent performance (perhaps a little bright) to my ears. I am thinking 'bout adding a valve based preamp to the Krell. How would it be? Or as advised, I may completely switch over to the tube amps.

+1 Black Ice Audio Fusion integrated in your price range. I've had the RF-7 in my home and also found the Fusion F22 with EL34 output tubes to be ideal. I even ran my DIY SET 300B monos (8W); no problem driving these speakers to high levels in a fairly large room. The nice thing about the Fusion F22 and F35 is that, with the built in and easy to use bias meter, you can roll in EL34, KT77, KT88 or 6550. I've been playing around with quads of Gold Lion KT77 and KT88 I purchased from Jim McShane on my F35. You can't get this variety of sonic and power output options with any solid state amp.

BTW, Black Ice is raising all their prices by 20% on March 1, so if you're on the fence, this would be a good time to pull the trigger.

Good luck.

I may completely switch over to the tube amps.

It's not your gear and changing to smoother gear will not correct the problem. A crossover upgrade and perhaps a tweeter diaphragm change is what you will need to do. Talk to the experts at Crites or GR Research.