I turn nearly all of my electronics off after listening. The only thing left on is the internet-modem/router. After powering up for listening, consistently the music sounds better after at least 1-hour of warmup. I'm not certain which components need that hour of warmup however some of my best listening happens in the evening and after the system's been running for hours before. Many of you I'd bet experience the same thing. My preamp has no easy to reach power switch and the mfg. says to leave it on unless you're not using the system for an extended period, however I shut it down. All of my amps are class-A so leaving them on 24/7 is not an option I choose. I've never left equipment on past my listening time unless it's purely by accident. And while I can't comment on improvements in sound over longer periods of time with equipment left on, I think it's whatever you feel/hear from doing it that should be your guide.
Amp — Leave on or turn off
I always turned my Benchmark AHB2 amp off after use every night. After all, why is there an on off switch on the front panel if not to do that? Last night I accidentally left it on. This morning, when I played my first record, I couldn’t believe my ears. The same record I played last night sounded infinitely better. I tried a second record and that, too, was much better.
I know there’s a debate on the question of leaving an amp on all the time.
I now know where I stand!