Hello Hickamore
The manual on my FW F3 from Nelson Pass
states - "I do not personally see a reason to run the amplifier
all the time, but you can do that if you want to ".
"Also, at 200 watts it makes economic sense to shut
the amplifier off if you aren't planning on using
it for the rest of the day".
I'm sure this recommendation follows on my F5
and XA25. All of course running in full Class A.