Ive played through several "Lab L5" amps - back in the day.
Remember these same amps were used by everyone from B.B. King to Ronnie Montrose.http://www.rru.com/~meo/Guitar/Amps/Lab/
The interesting feature of these amps for me was the built- in Compressor, that was enabled the more you turned the compressor knob "counterclockwise".
But back to "wearing your ears out" - many working sound professionals I know understand their own ear's changing frequency response as a result of fatigue, hours, and decibel level.
It might help if you can locate a set of calibrated test tones and use flat response near field monitors to create your own personal hearing test.
The idea is test your personal relative frequency response of your own hearing at the start of the session. Then perform a retest of your personal relative frequency response of your own hearing at the end of 2 hours of mixing, then after 4 hours of mixing, then again after 6 hours of mixing.
I know a few professional sound mixers, who can manually compensate the mix they are currently working on for hours on end, based upon the length of total time they have already been working on the same project.
They know how their own hearing gets fatigued and looses response at specific frequencies, and know how to boost / cut these frequencies so they can deliver a good product to customer, even when their own ears are fatigued and not to be trusted.