Most of the solid state amps I've had or heard in my system took MUCH longer to sound their best. The latest that I heard in my system was a friend's First Watt J2. It sounded very good from turn on, but delivered better dynamic shading and a large soundstage after it had been on for about 45 minutes. While that amp runs a little hot, I think it is one that I would turn on at the beginning of the day and leave it on for most of the day.
A friend's Krell, which operates in class A (so it naturally runs very hot) took much longer than that to sound its best, which would be a problem because that amp is one that should not be on all of the time.
The various solid state linestages I have owned, such as the Placette Active and a Levinson No. 32 stayed on all of the time. Both would sound lifeless if not fully warmed up. The Naim folks said that their CD players should be left on all of the time and take a minimum of a whole day to sound decent if shut off for a long period. They claim that optimal performance is reached after one week of full time operation. I think that is really overdoing the warmup bit, but, I don't turn it off because it is intended to be left on all of the time. My solid state FM tuner is never turned off even when the switch is in the off position (off turns off the display only) because the manufacturer thinks that it takes a long time for the tuner to become stable after it is turned off.
I know there are tube gear people who also don't turn off their equipment because they think it sounds better that way. But, for me, that would be WAY crazy, particularly since my amplifier runs four tubes that now cost $1,000 each and the linestage runs 4 tubes that are closing in on that kind of money too, and the phono stage. . . you get the picture.
