Make sure you warm it up a bit longer than your other amps when you put it on standby.
I'm not sure how true it is, but the guys in Sounds Great said that they take a bit more warming up. Something to do with having push-pull AB something or other using just one valve. (means nothing to me)
Hope you like it
sounds odd to me... i would have thought all tubes of the same type are going to warm to the same point, over a varying amount a time. and the heater in the tubes should be desighned to apply a certain amount of current to the heating element and from that you can work out the time taken for the element to heat the tube at the average room temperature.
i wouldnt have thought class a or class a/b operation would relate in any way to how long it takes your tubes to heat up. maybe it does.