I have a very odd problem that I would like to know if anyone else has had. I use my MDB-1 through to my Alembic F2-B through to a Trace Elliott dual band comp through to a Cable Factory passive DI and out to the board. No amp (I'm on IEM's). I am using the wall wart for the Raven Labs unit and for everything else. I cannot get rid of a buzz when I have the MDB-1 in-line. If I switch the ground lift it doesn't go away. If I ground lift the DI it doesn't go away. If I take it out of signal chain, the buzz goes away. It is like a higher buzz as opposed to a lower hum. I tried using the DI for a while when I first got it and it always buzzed so I stopped using it as a DI. I don't think I really noticed any buzz until I went to the Alembic preamp last year. I used to have a Bass Pod and it didn't have this problem when I only used the MDB-1 as a mixer before the Pod. Anyone? help.