Do you always keep the Amplifier powered on

When I had my Simaudio i7 integrated I left it on all the time, but on standby when not playing. This is strongly suggested by Simaudio.
"The Standby button disengages the input section from the rest of the i7's circuitry and turns off the digital display. However , when in Standby mode all audio circuitry remains powered up to help maintain optimum performance." (from the Simaudio manual)

All due respect to Schubert, but you don't turn off your refrigerator when you leave the house. I have been an appliance service technician for thirty six years and have seen appliances that came very close to starting a fire but haven't.
I would not be apprehensive of leaving the amp on. Whatever you are comfortable with.