Well i took a look at the drivers, they all seem to be connected well and in good working order.

I connected an Energy bookshelf speaker as the center channel, and the same problem is replicated, so my felling is that buzzing note is actually on the source recording. I think the VP150 is a better speaker and just exposes the flaw in the recording more (and now with my new set up where the centre channel is more optimally placed i here the flaw more).