Speakers sound brighter at evening / night?

You mean Dr. John Nash Ott and while he discovered links to human health and light spectrum he did not discover the light sensors in our eyes that regulate circadian rhythm nor extraocular light effects via the ear which does not appear to directly effect mood but has mechanisms, perhaps chemical based, that helps SAD and does generate a mild brain wave change.

Quite right. Memory failed on the first name. Ott may not have discovered the cells, but he identified numerous effects, which no-one took seriously for years and years.

Here's the thing. Why are you unable to make the same allowance? Why are you incapable of imagining anyone else being able to do something, simply because you cannot?

millercarbon, I know people can do things I can't do, and can hear things I can't hear. You may have better hearing than I do. You may be much less subject to perceptual shifts than I am. But that doesn't definitively explain what bwang29 is experiencing. I don't perceive speakers to sound brighter at night. Do you? If they really are producing brighter sound, then that should be easily measurable. If the brightness is really there but it's not measurable, then we have an interesting question of what exactly it means for the brightness to really be there vs it being a perceptual effect caused by the state of the listener's physiology. 

The only thing that will change "brightness" of a speaker at night would be a change in relative humidity coupled with a bigger room and moreso with limited absorption.


A poorly designed amp sensitive to AC voltage but seems unlikely.

More likely it is a day that thas desensitized you to low frequencies.