My MIT speaker cables took over a week to burn in properly when I first got them. Other components took various, but long, amounts of time, when new. I don't claim to have the subtle ear of many who post here (I am not saying this tongue-in-cheek) but have not noticed too much of a difference when turning my equipment on once everything is no longer new. There is a bit of difference -- but I'm not sure if my ears are burning in or if it is the equipment -- I assume the latter. But that burn in is nowhere near as audible as the initial period. The differences are smaller (to me) and I would rather face the smaller electric bill. Since my equipment is solid state, I can't speak for tube gear. Cheers ;-)
P.S. Since I think you asked, my system is fairly decent with Sierra K2 preamp and Danali amps and Montana KAS speakers. I had a couple of Bryston/Thiel setups prior to that and also didn't really notice much, if any, difference once everything was broken in initially.
P.S. Since I think you asked, my system is fairly decent with Sierra K2 preamp and Danali amps and Montana KAS speakers. I had a couple of Bryston/Thiel setups prior to that and also didn't really notice much, if any, difference once everything was broken in initially.