Amp burn in time..just being on or music played?

No, the correct burn in time is the minimum amount of time it takes to exceed your ability to return a component to the dealer if you decide you don't like the way it sounds.
Cwlondon (System | Threads | Answers)

Ha! There is a great deal of truth in this.

I can't tell you how many responses I've read from small wire and component manufacturers (or their fan boy customers) who have told disgruntled customers that their gear required many more hours of burn in time beyond what the 30 day (or 14 day, or...) return period would allow.

If only they had put more hours on the component (thereby negating terms of the return period)...only then would they have realized how truly jaw dropping was the gear!

Clever.

Albert, I believe in break in. I've heard it many times, and most definitely with certain capacitors.

I have also read manufacturer's comments that I referenced above.

Look, I'm not saying trial periods are a scam. What I'm suggesting is if according to the manufacturer/fabricator their component requires more hours than is possible to accumulate during their trial period, then they need to expand their trial period to make it meaningful. Otherwise, the trial period is a useless marketing tool that benefits neither the customer nor the manufacturer.