Are you sure your not just hearing a 60hz hum from your electrical or ground loop, etc...? When I first got my new m80's and ep600, I noticed a similar buzzing sound like you describe coming from the 80's woofers and even my vp150. Once I removed the ground screw on my ep600, waaalaaaaa, no problem.

M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85