I just purchased a vtf-2 sub and 2 frnt def tech 350's 2 rear def tech bpx and the c2 center chnl. i wired the frnts and rears directly to the sub but got no sound. I then wired them to the receiver Denon 1803 and got great sound. I have 2 questions. why no sound when wired to the sub? If they are not wired to the sub I suppose I can't use the x-ovr on the sub can I? Any help would be appreciated.