I need to feed my home theater system with 5.1 audio out from my computer. But no input ports in my Home Theater. I have feed Computer out to IC STA518 inputs (TP702/TP704/TP705/TP707/TP708/TP11/TP713). But sound out is very low. Please let me know how to boost or convert computer output signals to feed STA518 IC. Circuit Diagram attached.
Your sound level is low because you are feeding the outputs of IC701 that attenuates your new PWM signal. IC701 must be disconnected for you to feed your new signals to IC702 and IC703.
EDIT: Its inputs are digital, not analog.
Digikey does not stock it anymore but they can order it for you.
Its datasheet shows how to connected for 4 channels output (quad), 2 channels output (stereo) at higher power or a single channel output (mono) with even more power.