If removing the other lead didn't do it then it sounds like the cable is mis-wired or the plugs are not making good contact.HI Technobear, thanks for taking time to respond. I kept the RCA connection to do an initial A/B comparison with the balanced connection. I detached the the RCA leads leaving the balanced connection as the sole source between the units but either way the sound is awful. My initial thoughts are that the balanced cable is faulty but I am also concerned that there maybe a fault with the Zen Dac. I need some advice on how to identity where the fault lies. Thanks
If you have a multimeter, you can check that the cable is wired correctly.
I assume you are fully inserting the plugs.