Audio Research D125 VS. Audio Aero Capitole Amp

Speakers: Quad 63 with Gradient sub.'s
Preamp:Audio Research LS15 with Great Northern Sound Mod.'s
Source: Opus 21 with Great Northern Sound Mod.'s
Interconnects and speaker cable: DNM

Current Amp is AR D125. I have the opportunity to move into an Audio Aero amp. Any advice to make the move or stay with AR amp?

I don't know the Audio Research amp you're refering to but can comment on the AA amplifiers. I've owned the Capitole 50 and found it very resolving. Smooth, open and true to the front end components. I currently have the AA Prestige monoblocks and have yet to hear an amp that exceeds the overall balance of this set of tube amps. My experience is limited of course by the others I've tried, but you will definitely will not be disappointed with anything AA manufactures. They make arguably some of the best cd players in the past 7 or 8 years and their amplifiers although less well known are wonderful. If the monoblock Prestige (no longer made) ever show up on the Gon, snap them up.
I had one AR VT100 mk2 , and nnow the audio aero capitole amplifier 50 watts classe A, no doubt audio aero is very superior the AR vt 100, I do not know other amplifiers better than this audio aero, I would like very much to buy the SET monoblocks that now are out of fabrication.
Get the audio aero, put 6sn7 of good nos like sylvania , and you will listen a fantastic amplifier.