Here's the specs on the Card.

Audio Specifications:

Signal-to-Noise Ratio: 104dB (typical, A-weighted)
Total Harmonic Distortion +N: 0.009% (typical)
Frequency Response: 20 Hz – 20kHz (notice no +/- dbs)
high quality 24-bit data converters
5.1 channel Surround
Coax and Optical S/PDIF Digital Output
DS3D and EAX supported