How Much Hiss Is Normal?

I have some Quad 12L Actives that I'm still setting up. I notice an ever so slight hiss from the speaker even when it's not connected to anything. You have to be right next to the speaker to hear it though. The volume setting does not change this. I'm reading that this is not uncommon for (other) powered speakers. They are both connected to a power cord surge suppressor. I assume this is normal??
Nothing is perfect, not even amplifiers. As long as you don't hear the hiss from your listening position, forget about it and enjoy the music.
Over the years I've owned many different combinations of amps, preamps and more recently several integrateds. Slight hiss or hum at speakers is not abnormal. Some amps had more than others but I wouldn't necessarily correlate the amount of noise with sonic quality once the music starts.
Swap the two speakers and see where the hiss goes. That will tell you if the spkeaker itself is to blame or amp (more likely). As others said, if you can't hear it from your normal position it is not a problem.
I have a vandersteen sub and Meridian active speakers that occasionally pick up some hum or hiss, but it's never a problem when listening. I've found that in my house, the source is the wall power and have dealt with it via power conditioning. You might try some power condition (on a test basis--don't buy unless it works). This could be hash on your AC line. A surge suppressor might even be contributing depending on the circuitry in the suppressor. Good luck and don't sweat it.
My rule of thumb regarding hiss is that it should never be more than 10% the spl of the total harmonic distortion of the amplifier driven to RMS clipping into the load you’re listening to. If it’s under that figure, usually you’re fine. If it’s over, you should be concerned: very concerned.
If you have tube equiptment, a hum is all to common. Even you can hear noise from SS amps. The king of hiss is my beloved Reel to reel 4 track. However, if it does not interfere with your listening experience I wouldn't worry about it.
I have two pair of Quad 12L Pro Actives and every speaker has some or two more than the others. I don't hear a thing at all from more than 2 ft away. From my listening position, it's dead silent and NEVER intrudes upon the music. No sweat at all.
It all dependssssssssssssssssssssssssssssssssss :)