I believe standby mode in tube amps usually refers to removal of high voltage to the plate and screen/control grids. The heater usually remains on which is the visible glow you see. You have the benefit of thermal stability without the degradation caused by high voltage stress.
Audio Aero Capitole MK II: Performance & Problems
Capitole MKII users, kindly update on the sonic virtues but also on any repeated technical problems. No forum postings since a week! Have these problems stopped? I understand that some units needed a software update; have these been recalled? Does the performance justify the high price? Please contribute.