Hiss noise from speakers

The problem is not exclusive to separates -- integrateds and receivers do the same thing. As Aball said, it is pretty common. That said, some preamps are more noisy than others and many times the noisier ones sound better (but not always). But if I had to choose, I'd pick a moderately noisy piece that sounded good over a quieter piece that sounded worse. Perhaps you will find a quiet preamp that also sounds good...

Just to further complicate things, consider that the noise could be from any piece of gear in the front end of the system. Try the preamp switched to an input that has nothing connected to it and see if the noise is the same. If it's lower, then the noise could be coming from your source component and not the preamp. Also, some audio cables exhibit more hiss/noise than others...

I think this is a very common thing. I can't think of a rig I've assembled in which this "hiss" didn't exist at some level. The degree varies from preamp to preamp. It was a big problem with an Exposure preamp I had, which was a really great preamp in spite of it. I was told that a common method to reduce it is to place caps on un-used RCA inputs. I just decided to quit worrying about it instead.

Air leak-have your speakers sealed.

All electronics have some noise. If you have to put your ear to the tweeter that is normal with the volume turned up or a tube piece.

Don't put your ear up to the tweeter.

"Doctor, It hurts when I do this."
"Don't do that"