I haven't seen this pair of units in a long time but as I recall, there is a control cable that goes between the 80-8 and the DX-8. Outputs from your console go to the dbx record inputs. dbx record outs go to the machine ins. machine outs go to dbx playback inputs. dbx play outs go to your console tape machine returns. There shouldn't be anything left over, assuming you intend to use all 8 tracks.