On the video you provided, it sounds like static interference and not true "feedback". So it could be electrical interference from the computers you're using and as such, have you tried using shielded speaker wires?
Have you made sure all microphones are turned off when the speakers are on? Cordless and wireless telephones can cause such interference. Have you removed them all from the speaker proximity?
Have you updated the sound card's driver? If not, visit the sound card manufacturer's website and download/install the latest driver for your card. The driver should also be available at your computer manufacturer's website.
Hope this helps.
Grif
I have a set of speakers I have connected to two computers using an IOGear KVM device. I am getting feedback in them from both computers. I thought it was the KVM device so I bypassed that and still get feedback. Next I tried new speakers- the feedback still exists. I then thought my charging stations may be too close and are causing some sort of interference so I unplug it- feedback remains. I actually bought a new desktop (not for this reason) and the feedback is still there. I even moved houses (again, not for this reason) and still have the feedback. When I plugged in my ipad to the speakers, the feedback was gone. I am attaching a video of what it sounds like. This is not my system, just something I found on youtube to demonstrate it. Also, I think it may be getting worse than what it used to be. Any information would be helpful.
Thanks
https://www.youtube.com/watch?v=ubtUjCM_kjo

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