We were asked if the XLe uses the PC sound card.
Answer: No.

Both the XLe and XLi have our own HD Audio device built into our PCI-e card, neither use the PC sound card.

The XLi takes four of our HD Audio device outputs and the one external input (after converting it to digital) and switches them all to the 6 zone outputs where it converts them to analog and out to the output jacks, all on the card.

The XLe takes five of our HD Audio device outputs and the four external inputs, converts the external inputs to digital and sends them all out on a cable to the first XLe chassis. The XLe chassis switches them to the 12 zone outputs where they are converted to analog and outputted to the RCA jacks. It also forwards the digital signals to optional 2nd, 3rd and 4th chassis if you need more than 12 rooms of audio. The XLe also has triggering capability, as mentioned in the product page.