Class A amps do sound good very quickly after fire up,Because they (at least mine do) reach around 80% of their "A" bias straight away, the other 20% takes a bit longer once the heatsinks get warmed up.
This is why I always recommend "if you have the money", the Gryphon Antllion, as when switched to low bias everything is on, but it's only 5w bias, kind on your power bill, but warm enough so that when your ready to listen, you press 100w high bias and it gets there much quicker. Or you leave it at 5w for parties, background music, etc There is a 50w medium button, but I don't know what you'd use that for.
Cheers George