I use tubes amps. I warm them up no less than 15 minutes before use. I also let the amps cool down for the same amount of time before powering down. I started doing the warm up cool down many years ago and it increased my tube life nicely.
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?