Hi Adam W.
Thanks for the followup. I am really interested to hear the response. My friend, who is an excellent tech, re-biased my amp for Class A1 operations and set up the hybrid bridge rectifier. I finally am home and have a chance to listen. It is excellent, set up in this way. I am using Electro Harmonix KT88's, RCA 12bx7's in place of the 12ax7 tubes and some Sylvania gold pin primo 12au7a 's. This setup is wonderful to listen to. So the amp is inherently very good. I just want to know what the original bias setting were supposed to be, because mine were way off. Further, why do they advertise it as A2 when it is clearly an A1 circuit? And for a bonus, what is the explanation of the 5AR4? I have heard from an amp designer that even though it technically does nothing, that it improves the sound in some "magical" way. Hard to believe, I know... But maybe the Cayin engineers are magical thinkers.
Also, for you triode bigots, my friend changed the triode mode to pentode so that we could a/b pentode/ultralinear with the push of a button. I am thinking that pentode may be even better than ultralinear. Yes, I know that is not a very popular opinion...
With the original bias settings, triode mode was a non-starter. I guess we ought to check out triode mode with the new bias settings just to see if the the biasing was messing up triode mode. But I am betting that pentode may be the winner as far as my tastes are concerned. Call me a Luddite if you wish...