Warm up time for record playing

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. 

**** 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.

I’m glad to hear all the corroborating responses to my observations.
As is said above, It’s not mutually exclusive that physiology and warm up time are both possibilities.