I started out by disconnecting the Quickie from the ST70. With it disconnected the only noise I hear is from the transformers. I re-connected the Quickie and the hum returns at the level I normally hear when playing an album. I then dis-connected the MS23B from the quickie so that there is nothing connected to to the inputs, with the selector switch in the off position there is hum, and with it turned to select either of the input positions the hum became very loud. It has been suggested that I install a 3 prong electrical cord on my ST-70 but I seem to remember that Bob doesn't think that's a good idea. Any suggestions for solving this issue?