Is it the beer or do speakers/electronics really need some extended warm-up period?

I think it depends on both the beer and the gear. Drink enough and you're basically rolling off the high freqs. This becomes especially noticeable after 3 or 4.

SS class A or tube amps do seem to improve within the first hour while they stabilize. Some speakers, like my Spendors, seem to benefit from a good 30 min of warm up if they've been dormant for a while. Other speakers like my Heresys, don't seem to have that issue.

I've experienced systems sounding much worse after a few drinks, and the opposite as well. My main rig tends to sound better when I'm sober, but that's probably for the best.

Electronics and speakers (cone type) do in the sense of getting maximum SQ.  They do not _need_ it to work and sound "ok."

It may help to distinguish daily warm up from initial 'burn in'....

Interesting about some systems sounding worse with warm-up.

Yea, I didn't mean burn-in, just playin time.  I imagine components properties change after being stressed and the best designs account for this?

I think most audio manufacturers believe their equipment benefits from an hour or two of being powered on. At least McCormack and Ayre and Atma-Sphere recommend keeping things powered on for a while.
Bob