Mood

I was thinking also that it could be the power thing.  How late was it?  Super late should be fine it seems though.

Can't say I've experienced that phenomenon, but then I've only got music playing at certain times.... 

If it's my mood, then typically, I'll end up playing multiple disc's without feeling gratified by any of them... and end up switching off the system.

Sometimes the system sounds especially good and I tend to assume it's associated with power, although I could be wrong.

Of course, if there's actually a problem like sibilance, which, as it happens,  I've so far failed to solve, listening will just trigger frustration. My workaround is limiting my listening to instrumental music.

My mood doesn’t seem to affect my perception of the sound of my system. 

@ghdprentice 

You have a gift! I cannot rely on my audio perceptions because they swing so much. I noticed this back when I used to play string bass. It would sound rich, warm, and full to me one day, and then thin, raspy, and scratchy the next. I thought it was just me, but a lot of musicians report this same phenomenon. 

Just curious, do you have perfect pitch? I wonder if that makes a difference.