I'm returning the Panamax M4300 that I ordered. As soon as I plugged it in, there was a rather loud hum. I know, I know...I'm starting to sound like a broken record.
However, from what I've read online from other buyers, this is not normal. It should be silent.
I'm not too disappointed, though. The readout on the front is pretty bright, and there's no button to dim it. I don't feel like covering the voltage readout with tape.
Also, whatever noise my Belkin was making (which I could only hear when I was up next to it), I haven't heard it again. Still makes me wonder if it's going out, though.