Don't know why that would be. I only have a single Night Mode on my amp, and I don't have any audible distortion.
I don't have a great amp (Only a Pioneer 5.1), but my Kef iQ50 speakers would highlight any distortion in seconds! Since I have never detected any, I can only assume that my amp isn't creating any.
I think you will find the sound
is distorted, but you are not so sensitive to it. If you can live with that, good for you.
Any dynamic range compression is distortion. The mix of instruments will change in an instrumental piece, and, of course, their dynamic range will change too. That makes them sound unnatural. I have tried several times experimenting with the mildest compression setting on my amp and after a while find myself going back to pure sound because it sounds so dreadful. Plus, occasionally, when sounds get flattened into the voice range, it is even more difficult to hear speech!
Ezra: I agree with what you say, but dispute your claim that the compression is inaudible. It is very audible, if you know what to listen for. In fact, compression is one reason why LPs sound inferior to CDs IMHO.
I think we are all agreed, mostly, that it is the
mix that is at fault and not the Hummy, though. There is always a conflict between realism and audibility, eg, in a noisy environment on set, should dialogue be inaudible like in real life or unnaturally audible? (Building site, club, plane.)
Interesting discussion though.