I picked up a svp-pro. Two things have jumped out to me. Fisrt is I realy like the sound and tone of this thing. Second, it buzzes like mad! When everything is unplugged except the power cord and its turned on there is an audible hum noise. There is a slight vibration when you touch it as well that seems to match the noise. Is this tubes? I havent ran across this yet, have shows this week and need a fix. Thanks.