I have no idea if this applies....
Totally not knowing the inside or cabling for it. In the sound biz, any cable carrying low voltage signal is shielded with aluminum wrapping under the insulation around the wire. This is done to prevent leakage into the conductors by things like WIFI, RF, TV, Radio...and any other signal types passing through the air.
We had one incident when our sound system took on a radio station we could not get rid of. There are 100s of shielded cables we had to check, process of elimination. Turn out to be a XLR mic cable where on the inside of the connector the shield didn't make it all the way to the end of the conductors, therefore it leaked radio waves. Just the right problem in just the right location, ya just can't blueprint that stuff.
SO, when someone brought up tin foil, I instantly think of wire shields. If a cable gets moved a lot this can happen, or it could be a flawed cable. Inside the box cabling would have the same effect. Our now optic fiber cables do not have this problem, they are not shielded as they just pass data.
IF aluminum shields works, I would point to a cabling problem. This would also apply to HDMI and USB cables. They should be shielded. You could try just buying one new one and replace them one at a time with it, until you strike gold.
No matter what the component, 90% of the time I trouble shoot a concert sound system it ends up being a bad cable.
Just a thought, nothing more.
