As fuzztone reports, some amps have a slow start function. It limits current flow into the large power storage devices (caps and inductors) to keep from blowing fuses. If you have one of these type amps, then your manual will tell you so. I have an amp with huge capacitors (taller than the transformers) and it has no slow start feature.
So I just turn off my PP10 when I go on vacation and turn it back on when I return. If your component has a simple on off switch with no associated circuitry, then it makes no difference.
The second question would be whether your power plant likes to start up under load. my load is only 200 watts so I am not concerned.
Jerry