Oh, I agree totally, Joe. Vacuum tubes do require a longer time to reach thermal stability. And speaker systems definitely do sound better after several hours of use--simply because they are electro-acoustical devices with vibrating/moving parts (driver cones need to seat properly in their...
FYI, Lee: My skepticism regarding the claims of the high-end audio crowd is borne out of having once been a part of their ranks. I've owned tube equipment from Audio Research and conrad-johnson, and solid-state equipment from sooo many manufacturers. After years (decades, actually) of living...
Outside of speaker systems, no components require a break-in period. That's a myth promulgated by the snake oil-selling writers of the "high-end" audio press. Any decently designed electronic component only needs about thirty minutes to reach full thermal stability. Otherwise, leaving the thing...