The ASUS Xonar Essence STX is a PCI-e audio card that is designed for the music enthusiast. Equipping the Xonar Essence STX with the best components and the finest design, the STX delivers a top-of-the-line audio experience with a 124 dB SNR rating. With a built-in headphone amp that can power headphones up to 600 ohms and 6.3 mm headphone jacks, the STX makes a perfect pair with high-end headphones.