The STAC9250/9251 are high fidelity, 2-channel audio CODECs compliant with the High Definition Audio (HD Audio) specification defined by Intel. The STAC9250/9251 enables a two-chip audio and modem implementation by integrating the "System Side" functionality of Silicon Labs' modem solution. The STAC9250/ 9251 provides a direct interface to Silicon Labs' "Line Side" integrated circuit. This integration results in cost savings without sacrificing audio fidelity or modem functionality. The STAC9251 also implements a direct interface to two digital microphones, supporting advanced beam forming applications and resulting in increased quality of voice applications.