HT and 2 Channel System set-up question

I have kind of a crazy system set-up, and I’m wondering if there’s a better sounding or more efficient (without being more expensive) way of setting it up.

For starters, I have a top-of-the-line McIntosh 4300V receiver powering a pair of B&W CDM-1NT speakers. The Mac also has a “preamp out” which I have my B&W 675 Subwoofer hooked up to.

I just added an LCD TV with a DirecTV HD receiver and a B&W CC6 s2 center speaker to the room, but the Mac is obviously too old to accommodate this HT set up. However, I still want to use my McIntosh for listening to music. So here’s what I did: I purchased a relatively inexpensive Yamaha ht receiver (HTR-5960) and two a/b audio switch boxes from Radioshack. One switch box is hooked up directly to the McIntosh preamp out, with the “a” input connected to the Yamaha front left/right preouts (allowing my McIntosh receiver’s amplifier to drive my B&W speakers through the Yammy when watching TV) and the “b” input connected to the “b” input on the second switch box, which in turn is hooked up directly to the B&W subwoofer. In addition, the Yammy subwoofer out is connected to the “a” input on the second switch box. Here's a diagram to help illustrate:

McIntosh PreAmp Out-------[Switch Box 1a]---------------Yammy L/R Preamp Out
McIntosh PreAmp Out-------[Switch Box 1b]------[Switch Box 2b]------Sub In
Yammy Sub Out------------------------------------[Switch Box 2a]------Sub In

Thus, when I want to listen to the TV, I have both switch boxes set to “a” (connecting Mcintosh receiver’s amp {which my L/R speakers are connected to} to the Yammy through switch box 1, and the sub to the Yammy through switch box 2), and when I want to listen to music, I have both boxes set to “b” (connecting the McIntosh with the Sub).

I like having the Sub for music since the 1NTs are bookshelf-type speakers and therefore can’t handle some of my music’s lower frequencies. I could use the Yammy to power the L/R channels for TV (I currently have it powering only the center channel), but I thought the McIntosh would be a better fit for the highly sensitive B&Ws, and using a reversible a/b speaker switch instead seems just as troublesome. So is this the best way to configure my system? Or am I sacrificing too much sound quality by connecting my Mac to my sub through two switch boxes? Any thoughts would be greatly appreciated…