Beyond the mood or the state of mind or even the alleged power fluctuations, I have a few self-proclaimed and possibly unsubstantiated occurrences where if I'm having a cold or flu, or anything ENT related, the music almost always sounds like crap. You cozy yourself up in your sweet-spot, with a warm beverage of your choice, and you play your favorite tunes... only to find the whole experience underwhelming. The one time you need your rather expensive and socially eccentric hobby to stand by you, it lets you down. And as always, you look at the glowing tubes dispassionately and say, it's not you, it's me.