There’s a reason why most SS amps have the on/off switch hidden inconveniently on the back - they expect you to leave the gear running. As one commenter noted, though, yes, the components do deteriorate over time (I just replaced a Conrad Johnson amp that had run almost continuously for 12 years; over the last year I had noted that the bass response was degrading). Counterpoint is that the majority of electronics failures occur during power up. Pick your poison?
Amplifier warm up
I was plalying Boz Scaggs, "Silk Degrees" LP. After side one, I ate dinner. One hour later I played side 2. The second side sounded clearer, more vibrant with better sound stage. I have a Parasound P6 preamp and Parasound Halo A21+ amp. Is it possible that an hour of warm up improved performance?