I would first start with upgrading the parts in the deck. If it uses IC's I would look to upgrade those and upgrade the power supply caps, rectifier, in line resistors in the power supply, all caps resistors in the signal from input to output, and add better RCA connectors on the output or make a Balanced (XLR) output but you will have to find a circuit/schematic of the ICs that converts single ended to balanced >transmits>receives>converts back to single ended. Pick up the Randy Slone "The Audiophile's Project Sourcebook", this book has the circuits for these XLR's. I hope this helps you out.