This is a situation I had a problem with as well. I have a "theatre room" where a projector (Epson Cinema 400 on 110" screen) and 5.1 system (Logitech Z-5500) reside, and I wanted a second display in my kitchen, but I didn't need the 5.1 out there, and didn't want to hook up external speakers over and above the speakers built into the LCD TV (an Olevia 27").
This problem was compounded by the fact that I have an Auzentech audio card using the DTS Connect in any situation where SPDIF Direct Out wasn't used (during DVDs or Digital TV). I needed the DTS Connect for when I was playing games as I didn't want to hook up each individual analogue channel. So, not only did I need a Digital to 2-channel analogue downmixer box, but it needed to handle DTS as well.
Well, as much as I hate to push Creative's crap, they seem to have the only little box that solves the problem. The DDTS-100 will take any optical or coax digital signal and mix it into any concievable analogue configuration, from stereo to 7.1. I ended up hooking the stereo input on the kitchen's TV to the headphone output of the DDTS-100. Set it to a reasonable volume (to mimic stereo RCA inputs) and forget it's there, on the other side of the wall where you never see it again. It even has 2 headphone outs, if you want to hook up a second redundant display (I guess that'd be 3 displays in total, I'm working on it, believe me, I need something for the garage).
Here's the link to Creative's DDTS-100 page:
http://www.creative.com/products/product.asp?category=4&subcategory=136&product=9468
Yeah, it pissed me off that no combination of cards or configuration could get the SPDIF to run simultaneously with the analogue out, but whatever, it's in the past now and I'm happy with what I've ended up with.
Later,
Jeff