Warm up time for record playing

Given the varying opinions on the subject, why don’t you, for the first 45 minutes or so of your listening session, play a different medium such as streaming or CD, then put on a record. If you still hear a difference after a certain time, you have your answer. If you no longer hear a difference, you have your answer.

Frogman, what I say about the physiology of hearing is absolutely, incontrovertibly true. Just google Wikipedia on it. The ONLY thing that is changing is your ear. Why do you think they have warm up bands at concerts! Notice the warm up band never plays at full volume? In small clubs the volume is not as loud but I still notice I am a little uncomfortable for the first 5 minutes or so. Once I do get comfortable things sound much better. All the other explanations I have seen here are assumptions without any proof. This is how mythology gets started. 
Millercarbon, you are just joking right?

@thecarpathian, not a bad idea but unfortunately not necessarily true. You have to factor in expectation bias. In order to determine if one item sounds better than another you have to be able to switch back and forth. You can only pay attention to one item at a time. You can not evaluate the bass and the treble synchronously. Your brain switches between the two. It helps further if you do not know which one you are listening to. Expectation bias is very real. Magicians use it all the time along with the power of suggestion. 

My phono stage: on, always (as suggested by it’s creator).     TT and SDS: turned on/spinning at least 30 minutes before listening (for bearing lube, belt, whatever).        While warming up my ears, in anticipation of realistic SPLs (as mentioned above) and expecting my cartridge suspension to limber up, during the first two or three cuts; I’ll do a crossword or sudoku.      Unless pondering CD pits and digits, previously, I figure the rest of the system is still warming up/stabilizing, as well (lots of tubes).     The realism manifests, when everything’s warmed/turned up.     The second vinyl typically takes me, "there", better than the first.

**** Why do you think they have warm up bands at concerts! ****

I was not doubting your comments about physiology at all and I made that clear; only the degree to which it might be a factor. You lost me with this one, ‘though. I seriously doubt concert promoters are concerned with the “physiology of hearing“ other than the deluded notion prevalent these days that louder is always better. Building anticipation, giving the audience their money’s worth, or even setting a lower (not always) bar for the main act with a warm up band?  Sure. However, I have known a few and not once has the issue come up. Moreover, where’s the physiological “warming up” when attending a live orchestral concert, for instance? Does the third movement of a symphony always sound (!) better than the first. Not a chance.