Hi Paul, when I heard the ASR in a friend system it had been turned off completely - wasn't even in standby mode. It sounded very mechanical and distant - not at all like his system sounded with his Dartzeel amp. At the time I thought something must have been wrong with his system or the ASR was really bad - I couldn't figure out how so many positive reviews of the ASR could be written if it really didn't sound good... I experienced the same mechanical sound when I got mine and didn't have it in standby for a couple days. I now leave it in constant standby and it only takes an hour or two of full-on warmup to sound really good ;-) I have NO regrets with this amp and don't miss tubes at all ;)
Hope this helps.
Tony