3.1 A/V question

Hello everyone, I purchased this 5.1 decoder off ebay and I’m having difficulties getting it off the ground. It has dismal pre out voltage and my tv remote switches functions on it haphazardly. I’ve bought some cool little signal amplifier boards but I’m on the fence about dealing with the remote thing. It seems to break down the surround information into discrete channels which is cool but the remote glitching is diminishing the spousal acceptance factor.

https://www.ebay.com/itm/3254510898...UcG3IQTTzC&var=&widget_ver=artemis&media=COPY

If I can live without the rear surround channels is it almost the same to sum the L&R channels to mono for the center and subwoofer then just run the L&R signal for the front mains? I can input stereo analog instead of optical into the 5.1 board but the pre out voltage is still a problem. I understand that it just creates a faux surround sound from a stereo analog input so I’m not interested in dealing with the thing if I’m not getting actual 5.1.

I’m using the Dayton Audio Kabd boards in the receiver I built.

I suspect that it may require doing the L-R L+R thing which I don’t feel like doing. This is my stereo as well as tv sound and I don’t want to play with the mains music delivery.