Most Vizio TVs feature three ways to output sound from your TV to your surround system: HDMI, optical audio and composite analog audio. In most cases, HDMI is the preferred solution. However, the connections that your TV and surround sound receiver support, as well as the kind of cables you have or are willing to purchase, affect your options.
Things You'll Need
SPDIF optical cable with TOSlink connector, or
Composite audio cable with RCA connectors
In most cases, HDMI is your best bet if your cable and surround system are compatible with HDMI Audio Return Channel. While all HDMI cables transmit sound and video, ARC is designed specifically for using the TV as the source of the audio instead of the receiver. HDMI ARC transmits sound output from the TV to the surround system without an additional cable, which isn't possible in HDMI cables without ARC.
HDMI offers the best sound quality, because it transmits uncompressed or "lossless" audio, unlike digital audio or composite solutions.
Connect one end of the cable to the HDMI-Out port on your TV's back panel.
Connect the other end of the cable to one of the HDMI-In port on your surround sound receiver.
Turn on the TV and surround receiver and switch the receiver to the appropriate input channel.
Using Optical Audio
If your TV doesn't have an HDMI port or HDMI ARC compatibility, or if the HDMI port is in use by another device, optical audio is the next best choice. Optical audio uses fiber optic cables to connect devices and supports 5.1 surround sound audio. Optical audio cables come with the necessary TOSlink connector.
While better than a composite connection, optical audio offers slightly lower audio quality than HDMI because it doesn't support lossless audio. However, you probably won't notice the difference.
Connect one end of the digital audio cable to the Optical or SPDIF port on your TV.
Connect the other end to the Optical or SPDIF port on your surround sound receiver.
Using Composite Audio
Composite audio offers the lowest sound quality of all three options, but is commonplace on audiovisual equipment. If your TV doesn't support HDMI ARC or you don't have an available HDMI or optical audio port, composite is your only option with Vizio TVs.
Composite audio only supports analog 2.0 stereo sound. To get the most out of your surround speakers, switch to multichannel stereo mode instead of true surround mode. Otherwise, sound only comes from the front left and right speakers.
Connect the red and white connectors on one end of the cable to the color-coded L and R Audio-Out ports on your TV.
Connect the red and white connectors on the other end of the cable to the color-coded Audio-In ports on your surround sound receiver.