Looking for an external sound device

[RikuoAmero]

Hey guys, got my new gaming rig up and running. The only downside is I can't use my Creative SB X-fi Titanium Fatality Pro soundcard (the only slot I have available is a black PCI-E x16 hardwired at x4 speeds, and if I put the card in there, its literally only a millimeter or two from the second graphics card. Plus, when I do have it in, for some reason, I don't get a picture on the screen).

So, I'm now on the hunt for an external device. Here is what it MUST DO.

1) Be either USB 2.0, USB 3.0 or eSATA (I have eSATA data and eSATA power ports on the back of the case)

2) Have an optical OUT connection - this is to connect it to my Tritton AXPro headset (I've got the optical version, so I can connect it to my PS3 and Xbox 360).

3) Most importantly, it must re-encode all audio signals to Dolby Digital 5.1

What I mean there is, the Creative card has an option where all audio signals that the computer uses are on the fly encoded as DD 5.1. This is critical if I'm watching a Blu-ray or a 1080p MKV, as more often than not, they come with DTS tracks (not Dolby) and my headset's decoder box can't process DTS signals. I don't mind the down-grade from lossless 7.1 tracks to lossy 5.1, but hey, that's what the headset is, 5.1