I had a similar experience with a Rotel RA-1520 integrated amp. It might just be because it's class A and needs that initial warm up time? The devil is in the detail and, I'm not schooled enough to answer in a technical way but, just wanted to share my experience in case, it might actually be a Class A trait. I'm hoping my next integrated amp is a Musical Fidelity A220 and, let that be my end game.
