Mine pop on startup. I have two and they both do it. Other than that I am really pleased with them. Plenty of output to 4 ohm speakers and no hiss at all with ear next to the tweeter. The sound quality is clean to my ears and as good as the 20kg amp it replaced. I would have paid more for a silent start though, maybe I have been unlucky and got 2 faulty ones. I think both are out of warranty now so won't be able to return them.