OCC has published a review on the Diamond Xtreme External 7.1 USB Sound Card
A quote from the article:
Read more
The main excelling point for the Diamond card is the analog music playback, which was due to its ability to up-mix 2 channel stereo, up to 8 channels, which, was 6 in my case. It did a great job at making the room offer a fuller music experience, while the onboard sound without 3rd party software can only play in 2 channels. Everything else was very similar in quality and it was difficult to tell a difference between the two options since movies and gaming are easily configured for 5.1 or 7.1 through the onboard sound.
Read more