TechPowerUp posted a review on the ASUS Xonar Essence STX II 7.1 Sound Card
A quote from the article:
ASUS marked their entry into the high-end sound card market with the Xonar Essence ST some years ago. Today, we will take a good look at the new STX II. The STX II brings new op-amps and a more precise clock generator to the table; the latter should lower jitter. The STX II also bolsters 7.1 outputs through a small break-out card.ASUS Xonar Essence STX II 7.1 Sound Card @ techPowerUp