If an electronic component noticably varies over its normal lifetime it is probably of poor design or manufacture or defective. Either that or you are experiencing the normal human trait of adjusting to a new situation, i.e., it is you that is 'burning-in'.

No doubt others will disagree with my view. So be it. I am an electrical engineer and I have still not seen any valid proof regarding burning-in claims, only technobabble and the sort of talk that people who believe in the healing power of pyramids might use.

Cheers, Marshall.