Boomzbox is USB audio, so you shouldn't have interference issues associated with the cable between the Boomzbox and the computer. That means the interference must be coming down the antenna wire or is introduced in the power supply or thereabouts.
Just to confirm - you have NO interference noise when playing an mp3 or anything besides the Boozbox?
Ping Mitch on this. Hopefully he will show up and answer this post.