I warm most everything up for a half hour to an hour before I listen.
And some things I never turn off, ie..Yggy and my Jotunheim
even the maker of my solid-state integrated amp Anthem, recommends in the owner's manual you warm it up for a half an hour before listening.
I warm up my Lyr2 for around an hour mostly not for the tubes but for the entire amplifier to get toasty.
I do believe it sounds better this way. The magic doesn't really happen till it's
very warm to the touch.
I too leave my JggyB and Rok amp on all the time.
But I will listen to the 45 amp as it warms up just to hear what the SQ does as it morphs from 'cold' to fully thermally stabilized.
And it appears that these 'burn in hrs' are cumulative, thankfully.
And I really do wonder what the heck is going on that results in these variations of SQ as the hrs accumulate, because I'd REALLY like to make these sorts of behaviors stop, go away, cease and desist, but thus far, all of my fussing has done is in some cases just lengthened the time it takes to fully stabilize.
Sorta going backwards in this regard.
And since the 45 amp is still being fussed with, and on a semi regular basis, it hasn't had the length of time (not 10's but 100's of hrs) of no changes.
And the pattern has emerged that at ≈ 40+hrs (in this case, after I tweaked the 45's bias) there is a remarkable SQ step up, which I'm hearing even as I write this.
Elsewhere we use the term
REALNESS as a descriptor of SQ and when I hit this time 'window' of ≈ 40+hrs, that
REALNESS button gets mashed down, hard, and in no uncertain terms.
This is when the magic smacks you up side yer head.
JJ