I know that this issue has come up here before, but I don't think anyone had an issue to the extent that I do.
Basically ever since I built my PC about a year ago, I have been able to plug any number of speakers/headphones into it, no problem. All of the audio ports work perfectly on it. HOWEVER, I have one receiver (an old JVC) that always buzzes/pulses loudly when plugged into any audio port on the pc. I can plug an ipod or cd player into that receiver and it works perfectly, so I know there are no problems with it. Similarly, I know there is nothing wrong with my PC as stated before.
Now, what I have read elsewhere is that often having the receiver plugged into the same outlet as the PC can have an affect on it. I assure you, the receiver is plugged into a different outlet than the pc, and that outlet is on a different circuit. I originally had the receiver plugged into a surge strip with other devices, and have since plugged it straight into the wall to see if that would fix the issue. I have also tried the receiver on different outlets (including the same one as the pc) and all of them have the same effect. Work with any device but the pc.
I also tried the receiver in the front audio ports on the pc with the same result.
Honesltly, I have no idea what can be the issue. I have 3 other sets of speakers plugged into the pc along with a headset, and all of them work fine. I have tried unplugging all of them, and still the same effect.
Basically, if it's not the receiver, and its not the soundcard in the pc, and its not the same circuit, I can't fathom what could be wrong.
I tested moving the power cable from the receiver away from everything. No phones near it. No monitors near it. No other power cords near it. I'm now 100% positive that the buzzing is coming from the computer. Why it only affects this receiver I still cannot figure out. I tried the front panel audio on the pc and get the same buzzing.
YESSS!!! SOlVED IT!!! this has plagued me for a year. literally. Ok, what happened was this:
all of my other audio plugs have rubber shielding directly outside the metal plug. This one plug does have the shielding, but it starts up a little ways. basically, plugging the wire in all the way was causing it to pick up signals from the case. If i pull it out just slightly (not enough to affect the sound quality any) it stops. I can't believe it was that simple!