I'd call the company and see if you can talk to the engineer / designer. S/he will have opinions on this to be sure. They can tell you where the trade-off is between shutdown and simply leaving them on.
It isn't just the hours of idle time between listening it is also the amount of time you listen to them. Tubes can take a while to warm up and sound sweet, even though they are already playing music.
It isn't just the hours of idle time between listening it is also the amount of time you listen to them. Tubes can take a while to warm up and sound sweet, even though they are already playing music.