I'm just going to copy and paste from another forum:

"
Greetings,
Recently I have added a third video card to my computer which has sealed off access to all other
PCI slots, as well as the 1x PCI-E. All that is left is a SupremeFX slot for use with the similarly titled sound card provided with the motherboard, the quality of which is sub-par. I was trying to find a good way to achieve surround sound for games and games alone, for I have a Home Theater system for DVDs. While there existed the NX and some other external sound cards, none of them seemed appealing or of the best possible external quality.
In the end I came across the DTS-610 and was wondering if I could get some information from some of the more knowledgeable around here. Will the DTS, when connected via either the SupremeFX or another external sound solution, generate a higher-quality sound in games than using the SupremeFX alone (assuming, as I said, it is of middle-quality)? Also, my motherboard has both an optical and coax for sound and I was wondering if I used that instead of the soundcard, would I hear sound in games? As generally using optical or coax straight from the soundcard is only possible with DVDs and nothing is generated in games."

That about sums it up. There are no good external soundcards, so I need a way to get a good quality sound and I wasn't sure if the 610 was able to do that.

If anyone has any other suggestions about possible external soundcards or simply external PC sound solutions, let me know. Thanks.

Howdy. Looks like we are in the same boat (tri-SLI, ASUS mobo). I have been looking for a good solution also, and have not found any good external solutions either. For what it is worth, this is what I have been investigating recently:

adexelec.com

This company makes PCI extenders. My idea is to raise one video card and to put a cable extension onto my bottom PCI express slot. While I would much rather extend a full PCI slot for a soundcard, on my mobo (Asus P5N-T Deluxe), the 'open' PCI slot is in the middle, and the company only vouches for a 4" cable. They do allow 15" for a PCI express extender though.

I am still doing research on solutions though. Please post anything you might find out and I will do the same!

Will do! Also, if anyone else can assist, we would both appreciate it.

Well, I decided to go with the PCIe extender from Adex Electronics (link in post above). I selected the 15" model, which is the maximum length they recommend for PCI Express. My thought here is to actually house my middle video card outside of the box, allow access to the middle PCI slot. I will be putting my X-Fi Elite Pro in there. I like the idea of taking a vid card outside of the box as far as cooling goes. If this works well, then I may consider bringing all three video cards outside into a custom cooling enclosure.

The part number that I ordered is: PE-FLEX16-15". It will take them 2-3 days to build it and it costs $70. I will post the results after I set it up!