One more comment on burn-in, then I'll stop...but I was just reminded of it when I dropped my new SOTM "trifecta" stack into my system last night.
Aside from the soundstage effects you can sometimes hear that I previously mentioned...
One clear side-effect I very often hear when dropping in a factory-new source into a system (like a DAC, streamer, Roon endpoint, etc.)...the resulting PACE gives the impression of just the slightest, but very noticeable, perception of "slowing down" of a song that you know very well. It needs to be a song that you have listened to for years to really notice it. Often the tonal qualities, detail, and even soundstage are there as you would hope for, but something about it still doesn't sound "right"...and when you really listen, you can realize that the timing of piano strikes, drum strikes, guitar string plucks, etc...will sometime sound just the slightest bit delayed from what you are used to. LIke it's just slightly dragging the whole song.
It's a very strange effect, and I cannot explain why I find this to be true. And it almost always goes away after the first 24 hours of continuous play for me...it's rarely a day 3 or 4 or beyond thing.
I also noticed this same effect with new cross-overs (twice). I've never heard this with burning in carts for turntables or tubes (although I hear other tonal and soundstage changes there).
Maybe this is a caps thing?
Just wanted to mention that as something else you might try to listen for on a new piece.