Well, it's just the stock tube that it came with. Tried moving it from the surge protector (which I'd gotten a few weeks ago) to another outlet and voila, problem solved. Dead quiet on low or high gain on my Teaks. That was easy. Edit: Haha, just kidding. Of course it was dead silent, the connectors on the Teaks had come unplugged. Still humming. Like I said, this is with the stock tube.