Fwiw, I'm with Elizabeth, also listen to my system a lot when not tinkering. In my experience I've noticed during daylight hours the system still sounds great but it is influenced by outside ambient noise. In the evenings with less ambient noise it sounds superior to the daylight play. Light or dark environment does not seem to affect the actual sound. I believe that the level of ambient noise does affect the listening experience.
Bright or Dim?
Have you ever noticed that when listening to music in your listening area that music seems to sound better with the lights down? To me there is a rather noticeable difference. Could be just in my mind because that's how I like to listen, or is it something more biological/scientific than that? Could it be that the lessoning of one sense enhances the other? Maybe it's just me. Anyway I thought I would see if anyone else has the same experience. Im sure if there is an actual reason for this phenomena, that someone on this forum will have the answer :)