What else was on in the room. I am thinking about flourescent or halogen lights, dimmers, etc. There will almost always be some audible hiss with your ear to the speaker. It is really up to you to determine how much is too much. Then it comes down to making sure everything is very, very well grounded (I solved one hum/hiss problem by increasing the ground wire size of my antenna feed), using power filtration, and using ferrite rings on power cords and interconnects for RFI/EMI rejection. I have also noticed that using single-ended ground power cords, IC's and other connects (i.e. trigger cable) can sometimes help also.

I personally can hear a hiss on my POLK SDA-1c's with my ear about an inch from the tweeter. It is there with my M-200's and was there when I had Marantz MA-500's and Adcom GFA-565's hooked up as well.