I swear I have that cable somewhere in my house, but I couldn't spend too long looking. I did, however, disconnect the RCA inputs to the DSR1 individually and the clicking went away with left front disconnected.Get RCA to 3.5mm wire. Plug the RCAs into the amp, and the 3.5 into your phone. Play audio and check for noise. This will help pinpoint the problem as either after the amp, or between the amp and head unit.
I'll have to see what happens when I plug in another source