I’m 99% convinced it’s the ground of the electric power.
Make sure you plug all the electric plugs as close as possible in the same plug socket.
Maybe you can also help yourself be connecting a wire on a metal piece of the speakers with a metal piece on the interface. Or at least try, if the noise changes in any way. If yes, it’s a ground problem!
Unplug one device after the other ans when it gets better (to switch of the devices wouldn’t help!). Like this you can maybe find the problem too.
EDIT: btw: Balanced cables wouldn’t help in this case of a ground problem.
I would check for ground like matsteiner and others have said. But I also have a pair of hs80’s and their is always a hiss, even when everything is unplugged and off except for the monitors. Like dB said, these are known for being a little noisy.
Mine aren’t too bad and I have learned to work with them. When I’m tracking or mixing I don’t notice it, but when the music stops I can hear them.
It depends on the kind of noise.
A low constant hum is indicative of bad grounding – the ground in 2 components isn’t at the same voltage level (or something like that). For starters, you have to get your soundcard’s power source (the computer) on the same power outlet as the speaker’s, and try not to use long cables to the power source, or between the soundcard and the speakers (cable length adds resistance and changes the voltages which can create a ground differential). This is assuming you don’t want to hire a electrician to re-wire everything properly, or learn how to do star grounding, etc. Try other outlets as well as it could just be the one you’re on has grounding problems.
If it’s a constant hiss, it may be the power supply to your speakers. You may need it upgraded ie: the speakers themselves if they’re powered, or a better amp if they’re passive. If it’s a wall wart, look into a better built one or call the company and see what they say about other possible specs. I have an interface that was hissing for a long time, and a google search turned up that you could actually use a totally different spec wall wart for it (different voltage and AC instead of DC) and it would fix this problem. Worked like a charm…
If it’s RF noise, like little intermittent squibbly radio sounds, then you can try moving to a different outlet first, as well as moving other electronics away from the area. But if you just live in a bad geographic area, then look into better shielding. You need to make sure you are using balanced cabling if your hardware supports it. If not use short cabling (longer cabling = more surface area for RF noise to enter the system). Sometimes there’s not much you can do about RF if you’re in a bad area, and it’s a case of reducing rather than eliminating.
Also try turning things on and off throughout the house. Lights on faders, fluorescent lights and rotating electric fans are common culprits of all types of noise. I don’t know enough about electricity to understand how to fix those things, so when that’s happened in my many spaces over the years I simple leave the guilty party off at work time.
Good luck! -SP