Is 500 hours of break in really nec.?

Don't (feel guilty). Most components and wires seem to be happier when playing music rather than when silent, IMO. Particularly so when said items are new on the job (i.e., allow for induction period). Items display happines through better sound.
I say, take a positive outlook: despite the elec bill, you can listen to music whenever you want w/out having to reserve time for warm-up, then stabilisation, then sitting down to listen.

Enjoy the tunes!

Interesting, Liguy. When trying to gauge the effect of "burn-in" in the past, I would come up against a familiarity factor -- i.e., getting used to the sound of the new cable with time. In this respect, getting "better" (burn-in) could actually mean getting more "familiarised".

If (for the sake of example) "burn-in" is achieved slowly rather than in ear-catching leaps & bounds, the differences (again, assuming there are some such) would be small from one hr./day, to the next. Similarly, familiarisation may make these differences imperceptible.

I assume you've taken this into account long ago -- but your experience, being different to mine, is interesting.

Cheers!