My friend has a Sony DR-GA500 headset (review and info here) and is looking for a sound card for his new computer. I'm not very familiar with audio technology, but my understanding is that the decoder box that comes with the headset takes in an analog 7.1 signal and sends a "virtual" 7.1 signal to the headset. Does this mean that the headset is just receiving 2 channels but with 7 channels worth of audio data? Is the decoder doing the same thing that a Xonar sound card with Dolby Headphone would do.
I'm trying to decide between the Xonar DG or DX. I know the DG has a built-in headphone amp and 5.1 channels, while the DX has no amp but 7.1 channels. Both have Dolby Headphone. Which one should I pick and is there anything else I should consider? Thanks.