Was doing some recording this week with my 360/12. I went to record a lead part, used a compressor, and i was getting a low in volume distorted noise. Switched the compressor off and it went away, but bring the compressor back in and it came back right away. It's like a distortion coming from the pickups is being amplified when the compressor is on.

I know that it is the guitar, as i tried it with another amp with the compressor and it did the same, and I also plugged into another amp that has a built in compressor and it did the same. Easiest way to describe it is imagine a 12 string guitar going through a distortion pedal into an amp, at a very low volume. Put that in behind a clean 12 string guitar going through the same amp, and thats what it sounds like.

Very wierd, and very annoying. I love compression on a 12-string, but this is making it unusable.

Anyone have any experience with this?

Try cleaning up the contacts on your toggle switch, my 660/12 was doing something like yours when in the middle position (buzzy noise).

I just pinched a small piece of fine sand paper between the contacts and pulled it out 2 or three times and it cured the problem, worth a try me thinks.