How far away from the speaker can you hear it? If it's not audible where you sit, I wouldn't worry about it too much.

If you don't mind, what center speaker do you have, and do you know it's sensitivity? And what power amp do you have powering the center? I have found that above average efficiency speakers with certain high power amps can give you a hiss combination. One thing you could try, is to see if the hiss changes volume much with the 950 off or not.