Heaven or Hell

Well after reading the responses I have to qualify my statement. There are times when the music just isn't as engaging. Not saying the system sounds worse, just that my level of interest isn't as high.
On those occasions I wouldn't have the interest to listen for changes.
How many of you listen intently every time you sit down? That's another thread I suppose.

There is undoubtedly truth in all the replies. I have personally seen tremendous differences in how engaging music was that were ultimately attributable to variations in power quality... so I suppose I must throw my offering to the stereo gods into that pile rather than psychoacoustics.

Good or bad mood going into it, music typically re-frames my perspective. That's a big part of why I think we are here. If instead my mood purely dictated my emotional response to music, I would likely listen a lot less...

Dedicated lines and well-thought out power solutions have really helped many 'goners who listen in crowded population areas to experience greater consistency; your recent experiences may be a sign to look further down that path perhaps

I can remember discussing this topic with some audio friends back in the late '80s. It is certainly not new or an uncommon phenomena. Some of the things we listed as possible causes at the time were: air temperature, humidity, frame of mind, and quality of power coming in. (One buddy had a 1 Farad, that's right 1 Farad capacitor in his basement to filter incoming power. ) We also suspected that sometimes maybe capacitors in the amp/preamp take a set a different way once in a while and can make the music seem dull. (We had mostly tube gear).
I have a pretty constant turn on and warm-up routine for my equipment. It sits minimum 1 hour before I play anything. I will wait several hours if the equipment has been off for several weeks.

If you are technical rent a Fluke 43b power quality analyzer for a month (about$200) and connect it to the AC outlet.

You will be monitoring and logging everything about the AC.

This will tell you if there are any problems, and exactly what happens day to day.