Since you have a stereo integrated amp it would be simpler to use a DAC like this one
http
/www.parts-express.com/parts-express-dac-digital-to-analog-converter-%2851-compatible%29--180-999
rather than a 5.1 decoder.
Connect the optical out of the TV to the DAC with a toslink optical audio cable. The DAC connects to any input on your amp except phono with a stereo RCA cable.
The EQ connects to the Tape/Adapt input and outputs with stereo RCA cables The record out on the amp connects to the input of the EQ. The output of the EQ connects to the playback input on the amp. When you want the EQ to affect the sound press the tape monitor button on the front.