strange buzzing issue

[daz]

I have a homebrew JCM type amp that i'm getting a buzz in. It sounds like single coil buzz and the guitar i don't think is the issue because it does it with all guitars to one degree or another. My HSS strat has a dimarzio HB and 2 van zandts does it the worse. And some HB pickups are pretty much quiet to a normal degree. The dimarzio is 4 conductor and it IS wired correctly. In fact, i haven't touched the guitar's wiring in a long time and this issue just started. If i touch the polepieces the buzz gets real loud. And YES, i know this typically means the guitar's plate has a ground thats also connected to the hot and the other side of the coils is grounded such as when one reverses the pup to phase it correctly with the other pups. But this isn't the case because the plate has it's own seperate ground and each side of the pup has it's own wire so they can be swapped. (and of course the middle connection between the coils which is connected to a coil cut switch)

heres why i don't think it's a guitar issue....if i plug it into another amp (tried 2 so far) it doesn't do it at all. In fact, not only is there no buzz but i can touch the polepieces and no noise at all. This like i said is an odd issue ! What could be happening in my amp to make that happen when i touch the polepieces?! in any case, thats not the problem, the problem is the amp buzzes regardless of whether i touch the poles. Touching them just seems to be a symptom of whatever actually IS the issue.

I realize this sounds like some sort of ground issue, but i have tested every ground in the amp. Any ideas?