Northernguitarguy's point is major. There's hum, and there's HUM. I don't like P90s much, and of course they hum, but unless there is something way off, it is not as load, distracting, or bad as what you describe. Plenty of players who love P90 tones get by with them as stage guitars because, again, it should not be that bad! There are too many possibilities for hum-generation than I want to write about, but the info is all over the web. You're not standing under a fluorescent light, playing along with an old TV two feet away while using an ungrounded tube amp next to an old electric fan, are you?