If you are using an AV receiver (which you are), then the quality of the components on the sound card is of less importance. It only really matters, if you are using headphones, or speakers with analogue connection.
By using digital connection, the sound card (which ever it is), is not doing the sound processing. The AVR will be doing that.
The only real important thing when deciding between a DS and a D1/X, is the real time 5.1 encoding capabilities, which you may want to use, depending if you are going use your speakers for gaming or not..
The DS can encode to DTS 5.1 on the fly, whereas the D1/X has Dolby 5.1. Your receiver can decode both, so it just comes down to whether you prefer one over the other.
If you are not going to use it for gaming, and will just use it for DVD's etc, then it doesn't really matter which card you go for, as both will pass on DTS and Dolby 5.1 tracks from a DVD to your receiver for decoding.