Yeah, does the noise level go up and down when you move guitar around and change pickup settings?
If you move around parallel to mains power etc sound like this can change if from pickups.
Also light dimmer switches can cause noise like this, even if “off”.
Honestly shit like this drives me crazy. If in house I’d go to breaker and shut off everything but room you’re using just to see what happens.
I’d borrow a radial JDI and xlr to ts just to see what happens too.