Just got my GL2 a month ago and I've noticed a hum when I connect my Sennheiser headphones into the headphone jack. I've yet to try another pair of headphones but I was wondering if anyone else has ever had this problem. At first I thought it was camera noise but even my old, cheap Sony DV cam never sounded like that. Luckily, the hum isn't captured (just standard camera noise) but it makes it difficult to listen to ambient sound when you're recording. Switching to manual audio doesn't help but switching to Wind Screen mode does dampen the sound (Voice sounds pretty much the same as Normal).

Any ideas?