My system is Rotel RA02 amp, Rotel RCD 02 CD, Quad 11L's, Marantz DVD 4200. I have a powered subwoofer (PSB Subsonic 5) that I want to use when I use the system for DVD's but not for music - the Quad's don't really need a subwoofer for music. How can I connect the subwoofer so that it only comes in with DVD's? Can I connect it to the B speaker terminals of the RA02 and then switch to A+B when I watch DVD's - is that risking damage to the RA02. I would welcome anyone help or advice on this.