So, a few months ago, I bought an Intersound IVP. It was working great, nice and quiet...used through rehearsals and roughly 3 or 4 gigs. Well, the last gig it was used for, it was buzzing like crazy! I narrowed it down to the IVP, after going through all the rest of my gear. I brought it to a shop and they went through and "checked" it all out and cleaned pots. They stated they tried the preamp out with an amp there and it was dead quiet, sounding great. However, once I got it home and tried it, the loud ass buzz is still there! I've tried different cables (all high end), wall outlets, guitars...etc. The shop told me that it could be the preamp not agreeing with something in my amp (Mesa Boogie Mark I). Is this possible?? Has anyone else had this happen? I'm totally at an end with this thing! Could somebody please shed some light and give me some info? It'd be grately appreciated, thank you!