The MyWirelessTV3 Transmitter supports 5.1 surround audio input and pass-through. The Receiver supports support LCPM stereo audio out. Begin by verifying that the AVR is compatible with 5.1 channel audio. If it is, it may also be required to verify that the Audio Settings in the AVR are set to either LCPM (PCM) or Dolby Digital. Please contact your AVR manufacturer for assistance verifying and/or changing these settings.