The very best I have heard my Quad US Monitors sound was with the Unison Research Smart 845 monos...25 watts per channel single ended. However, my experience is that with the Quads 25 watts from one amp may work while 25 from another may not. I also thought that the Cary 572s sounded good...20 wpc...but not in the same league with the Unison.
Good luck...you just have to try amps until you find the one that sounds "golden" to you in your price range.
Good luck...you just have to try amps until you find the one that sounds "golden" to you in your price range.