ASUS has another solid product for their Xonar line-up in the STX II. The addition of 7.1 connectivity is a bonus to some, but I doubt it will be a decider for the majority of gamers and music afficionados out there. What will appeal to everyone is the addition of several op-amps in the bundle, which allows you to tweak the sound to your liking without having to pay absurd retail prices through aftermarket vendors. The Muses op-amps have a somewhat different tonality compared to the TI-manufactured LME49720s, one of the most widely recognized high quality op-amps for audio products out there. The Muses bring a bit of warmth to the sound, which many people prefer.

Overall, the quality of on-board components has gone up from the STX. The caps are mostly from WIMA and the DAC and op-amps are some of the best chips around. A bit annoying is that ASUS has not engineered a way around the high output impedance of 10 Ohm, so TPA 6120A2-based cards are less than ideal for in-ears and super-sensitive headphones.

Since the card is available both with and without the 7.1 add-on card, it is easy to get the card that fits your needs. The STX II continues where the STX left off and is noticeably better across the board.