Two comments.
I used to have a Bel Canto S300 amp and there was no hiss whatsoever, even with my ear to the tweeter. It was dead silent. I don't buy the explanation that class D has an inherently higher noise floor.
Second, is there a source connected and on (but not playing) when you hear the hiss? If so, the origin of the hiss could be the source and a gain mismatch between it and the amp.
I used to have a Bel Canto S300 amp and there was no hiss whatsoever, even with my ear to the tweeter. It was dead silent. I don't buy the explanation that class D has an inherently higher noise floor.
Second, is there a source connected and on (but not playing) when you hear the hiss? If so, the origin of the hiss could be the source and a gain mismatch between it and the amp.