I need some sage advise. My Trace V6 is a little hummier than I'd prefer. How do I go about trouble-shooting a solution? Where is this type of problem most likely to occur? Preamp tubes? Power tubes? Somewhere else? It only happens when the standby is off and it's volume doesn't increase as I increase gain. So it's a steady level. It doesn't matter if there's anything plugged in. It's just there when you're ready to play -- and it's too loud for softer gigs. The tubes are about 4 years old -- and not gigged a lot (which says more about me than it does about the amp!). Thoughts? Need more info? Thanks!