Audio High Definition Audio 3D Enhanced Sound System S/PDIF Digital Output Built-In Microphone THX TruStudio Pro 7.1CH Audio output supported by headphone, microphone, S/PDIF & Line- In Jack Models A & B: 2 Built-In Speakers and One Sub Woofer Model C: 5 Built-In Speakers and One Sub Woofer Model A is P150HM, and model C is P170HM. Regards, Julian