Warm-up time.

Warm-up is definitely a phenomenon...and I can hear the transition. It's not distinct like going from dark to daylight but it's as much a revelation once you're in-tune to it. Speakers are affected as well. I give up my system for Lent. When I power up Easter morning, I am dejected because it sounds like a big waste of money. I have to remember it's like having a knee-cast removed after 6wks. Everything's stiff as hell. But after a couple days, it's back in the groove and so am I. 

When I had my Atma-Sphere rig, a 1 hour warm-up with no music playing was sufficient (but necessary).  Later on, with an all-Rowland system including a Model 5 power amp, that amp just sounded better and better the longer it was on.  When I was off for the weekend, I would leave it powered up all the time.  It did sound okay after about a 30-45 minute warm-up; the Capri preamp was always on as was the CDP.

My components "warm-up" while I'm listening. Kind of like a "first-set" of music type of thing. Once the first set (1 hr?) is over, it stays on during the between-sets-break (20 min?). Then onto set 2. Most band saves their "best" for the second set anyway, and by the start of the second set everything is warned up. :)