does your system "warm up" and then sound better?

Yes. Speakers. They have bits that move. It's the moving bits that make noise by vibrating. We call this noise music. Vibrating bits vibrate differently at different temperatures. Different kinds of vibrating will make different kinds of noise. It's, like, science. You could call it, "warming up." It's not (just) in your head. Things just start to come together and cohere just so-ly after about an hour with every set of speakers I've ever met.

As for the electronic bits that just sit about and pass electrons, all passive and not moving like, folks'll tell you warming up matters. I leave mine on all the time 'cause it's easier than wondering why I've never heard any difference. But, been years since I've really turned any of it off, so what do I know.....

Speakers. Let me take another stab, in case I was being too obtuse.

Think of your car. The mechanical work of making a car go happens in the engine. Engines tend to work better once they've warmed up to operating temperature. You know, friction and tolerances an expanding and contracting materials at different temperatures. Often, the higher the performance, the stricter the mechanical tolerances, and the more warming up matters. Your engine doesn't give a damn if you leave your lights on all the time. Sure lights'll be all warmed up ahead of time, good on ya, but you still have to actually run the engine to warm up the engine.

So, barring a few gross over-generalizations, what's the fundamental difference about warming up speakers even if the standby light on your CDP has been on for nine years? There isn't one. Yes?