Best power amp for Quad 63

all the amps you mention should work well, if the amps themselves are working well

Thank you. 

I am using an Ayre VX-5 Twenty. Perhaps a used unit is available.

Quad 606

I used an ARC Classic 60 when I had Quad ’63s- they were Crosby modified. That amp was not as warm and "juicy" in the old tube sense as previous ARC amps I had owned and used- Dual 75a (still have it, sitting idle); Dual 70 mk ii (nice amp).

At the time Crosby was doing the mods, he was working with Spectral. Though the Spectral sound was, to my ears, very analytical and "accurate," it lacked what I believed were some of the ambient cues-- but if those are on the recording, a good solid state amp, like some of those you are considering, should convey that information. They were used as part of a system, the Crosby mod on the ’63, the Spectral amp and big Entec subs. I heard that system more recently- within the last 20 years and it held its own.

I’ve been doing horns for a while- easily as transparent as the Quads in the mids- (I still use Quads in another system, a pair of ’57s I have owned since the early ’70s, with Quad II amps/GEC KT 66s, etc.).

The 63 may be a more overall reliable speaker than some of the later ones, which I never owned. Good luck= there’s music in them hills. :)