I have reacently been presented with an interesting theory...but first, let me tell you how I arrived at that theory. I had an Ibanez bass, which when playing the cable would occasionally become ungrounded, and all you could hear was that loud hum. THen it would return to normal. Tried different cables, but same thing happened. After making sure that it definatily was the bass, I took it back to the store, where of course it worked fine. Finally, I switched the input jack....same problem. I got tired of the bass and got a new one (another Ibanez, but different model). Although not nearly as often, still run into the same problem occasionally. Also, a friend who also just bought aan Ibanez is having the same problem. It's definatily not anything like the amp, cables, electrical interference... The guy at the music store I was at the other day told me of his personal theory that the tips of cables are slightly different sizes, and that maybe that certain brands would work with Ibanez's , cause whatever they use at the store works fine. Anyone ever heard of this, or have any comments on this???