It's always wise to be nervous around electricity and circuits. Solid state amps are normally run at much lower voltages than valve amps, but with correspondingly higher internal currents (when running) to compensate for that. But if you don't have access to a schematic to check, and know how to read and interpret it,then play safe and for solid state amps allow a few hours for the caps to discharge after turning it off, and wait a day for valve amps (if you haven't got a capacitor discharge probe).