Are you talking about new kit? In any event leave it running as you suggest at low volumes for about 2/3 days and you’ll start to hear it something like full performance. Speakers take longer in my experience. Some people claim that it takes 9 months for a ND555 to be at its best. A load of nonsense in my opinion, how would anyone objectively measure such a change over that kind of period?!
From new? Allow at least 2 months with it switched on 24/7.
I tend to leave my ndx2 playing Internet radio when not using it. But I was also running in some interconnects too.
Saying that, I do find it usefull ( like any micro processor controlled stuff) to reboot once a week too.
Congratulations on your system. My best answer is 200 hours plus. The problem is that it is a gradual process and your ears adjust to the changes. Sorta like being around a kid every day as they grow up. One day they are 10 and 3 foot tall, all the sudden they are 6 foot 3 and 18 years old.