Hello.
You can connect this using the Component input. Simply connect the RCA wires (white/red) from the Maganavox to the component audio inputs at the rear of the Vizio:
Then select "component input" on the TV set and adjust your volume.
If your TV doesn't want to switch inputs because no video signal is present, try inserting a free-hanging cable in the Green RCA jack, which might allow you to change to this input.