TechPowerUp posted a review on the ASUS U7 USB Sound Card
A quote from the article:
ASUS manufactures many sound cards but only a few great USB solutions. In order to correct that, they launched a wide variety of USB-powered products, and we will now take a close look at the U7, a 7.1 sound card powered via USB only, keeping cable clutter at an absolute minimum.ASUS U7 USB Sound Card @ techPowerUp