bluetooth speaker making buzz noise

I know this isn't particularly Mac or photography related, but I'm assuming there's at least some people here who own iPods or iPhones or Macs that use bluetooth speakers.

I just bought a Sony 200ip speaker at Costco for $130 on sale. I'm still debating getting a cheaper one that might sound almost just as good.

Anyway, at first the sound was pretty good, but then I noticed there was a buzz in the background. When I mute it, it goes away but obviously I didn't buy it to play it on mute.

I'm just wondering- is this inherent to the fact that it's bluetooth connected, or is mine defective and should I get a new unit? Do your bluetooth speakers buzz as well?

p.s. it doesn't matter what volume I set it at, although the buzzing doesn't increase or decrease in volume as I change the volume, so louder music helps cover it up a little.