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…
whew. I think you need to go with what you like.

Switchboxes, in your system are to be avoided. McIntosh components really don't work all that well with them.

You might be better off with just splitting the signal with a simple 'Y-adaptor.'
Yeah, I know - I can get a bit long-winded at times.

Won't splitting the signal cause concurrent signals to be sent to the subwoofer from both the McIntosh and the Yammy? If yes, wouldn't I want to avoid this?
I'm not sure I follow exactly how you have it hooked up now, but you'd be better off removing the switch box from your system. You don't need it. If you want to use the McIntosh for your front power and Stereo, all you need to do is to connect your Yamaha Front pre-outs to one of your un-used inputs on the Mac (eg Tape in). Then when you want to play HT Mode, you simply select that input on your Mac.

The first time you do this you need to calibrate your speaker outputs. Select the 12 oclock position on your Mac volume control, or some other easily remembered position. Then your receiver volume control will drive the power amp in the Mac. It will also drive your subwoofer through the Mac pre-out. The only problem with this is you won't be getting LFE from the sub outputs - but it doesn't sound like you're getting that anyway.

I have used this set up and it works beautifully - and this has been discussed many times in other threads. Another 'goner explained it to me.

The other advantage is you don't decay your 2 Channel Mac performance with a cheap switch in the chain.

good luck . . .
Bdgreg nailed it, I do the same thing with my Sonic Frontiers pre amp and use Rotel for HT, the only thing you need to get in the habit of is making sure you turn the 2 channel pre down when you listen to music, mine is at a bit past 12'oclock wich matches volume output for HT, but I turn it down BEFORE I switch over to CD,SACD or Vinyl. Also your 2 channel will need to be on during HT but I bet you could guess that much.
If there is any way you can retunr your switch boxes then invest that savings into a good wire to run from the Mac to your Yamy for best results.
Thanks for the advice! The only thing is that right now, I am getting the LFE from the sub output on the Yamaha. That's what initially led me to use the switchboxes - one of them is connected to the sub, with one input connected to the Yammy's sub out (so I can get the LFE), and with the other input connected to the McIntosh (which I switch to when I want to listen to music). Is there's another way to take advantage of the LFE while still using the sub with the Mac?

The other problem is that my McIntosh uses up and down buttons instead of a dial for volume control, so setting a 'position' will be problematic...
I would use the swith box for the sub only in that case. So you take the pre-out from the Mac into the switch, and Sub out from the Yamaha to the switch, connecting the output from the swith to the Sub. I would be less concerned with switch induced distortion in this arangement since you're dealing with a narrow bandwidth.
It will be ok for volume once you get used to it.