Wow where to start? I was a tube guy since 1982 and Ayre made me switch. I've heard their whole product line other than a broken in AX5/20. Their ref 20 gear is at another level. It is the best of all worlds. Clean, detailed, inky black backgrounds, extended on both ends, tuneful, tight, no congestion ever, luscious and the list goes on. It's just real and fast. Honestly, I'd like to see them call it an AX-R/20 as I'm sure it will sound nearly as good as the ref gear just much less power. It's already so dynamic without ever being harsh. I've heard the ayre on various Wilsons, Vandersteen 7 down to my own Treo's to Focal to Rockports to Thiel 3.7 to Gallo to Paradigm sig 8 to Dynaudio to KEF Blade to Pro Ac and B&W. They are the first amps that just let you hear what the rest of your system is doing. Fast tuneful and quiet are words that come to mind easily.