I recently bought an external USB sound card, however after plugging it into the pc (windows 7 bit), I don't get sound from the rear speakers. I just purchased an external USB sound card that the system recognizes as C-Media Electronics, Inc. CM Like Sound Device. The audio. USB Audio--Environmental Noise Cancellation technology, allowing you and callers get free from ambient noise disturbances.USB Audio,USB audio chip · USB Audio,USB Audio Codec · Audio processing.