I have no direct experience with AYRE amps, but have reviewed Bel Canto REF1000 Mk2, and more recently Ref500M on Positive Feedback. The Ref500M article is a comparative review discussing audible differences with Ref1000 Mk.2 (also called Ref1000M). The article can be found at:
http://positive-feedback.com/Issue50/bel_canto500.htm
G.
http://positive-feedback.com/Issue50/bel_canto500.htm
G.