What is it with this urge to explain away the things we hear? Not explain- explain away. The implication is you didn't really hear what you know perfectly darn well you did. It didn't really happen. You only think that it did.
Poppycock!
If it was circadian rhythm then turning the system on stone cold in the middle of the night would sound better. There. See how easy it is to debunk this kind of thinking?
Okay so first off its not the speakers that sound good late at night. The speakers simply happen to be the end of the line where the sound comes out. But all speakers do is output the sound they are fed. So if the speakers sound better odds are its got at least as much to do with the sound going into the speakers as the speakers themselves.
The question then really is, why does the system sound brighter late at night? I rather doubt it sounds brighter by the way. Never heard that myself. More likely if you listen closely you'll realize its the upper registers being presented much more cleanly and clearly than usual, with greater clarity and extension. Not quite the same thing as brighter, which is nothing more than a louder or tipped up top end.
Whatever, the question really is, why? Why would there be any difference at all?
Several possibilities. Probably all together have something to do with it.
One, the system very likely has been on a long time. Mine continues to improve for hours and hours. Its easy to hear, and happens regardless of time of day. When the guys came up from Portland recently I left things on and got up early and warmed everything up so good it sounded better in the middle of the day than it usually does later in the evening. So that's one.
Another is line noise. Everything connected to the grid is connected to every other thing connected to the grid. Just how far away this effect extends I don't know. But I do know without a doubt things done to my meter 100 ft from my room have equal impact to things done right there in the room. Or if you don't buy that how about RFI? Radio waves are everywhere, and not just from radio stations radio refers to the frequency not the content. All kinds of chips and things generate RFI. Every wire is an antenna picking it up. Even if you believe your power conditioner has the magical ability to provide perfectly pristine power there's still all the wire between the conditioner and your system. Every wire an antenna. You'd have to put a Faraday cage around your whole room to even put a dent in it.
Finally, and this is a new one I have to credit Max Townshend: seismic. The ground itself moves and not just from tremors or earthquakes (which on a micro scale are happening pretty much 24/7) but also the ground moving from cars and wind blowing on trees and buildings. All this stuff sends vibrations coursing through the earth into our homes and right up into our systems. Proving this is a problem is as simple as putting springs under your speakers and amp and stuff.
"Okay, there you go again, millercarbon," I can practically hear people saying, "But so what? What's the diff?" Great question. Glad you asked. Happy to answer.
If you buy into the explainer-awayer line then not only is there nothing to be done, but there is nothing that can be done. Its in your head. Its your circadian rhythm. Its your double-blind bias. Whatever. Never mind. These are not the droids you're looking for.
But, if you buy into any or all of the "yes we actually hear it" stories this means there are real things you can do to improve your system in the here and now: leave things on longer, work to improve power and reduce opportunities for noise to get in, and put things on springs.
The choice is yours. Choose wisely.
