Doh!!! Found that cable mod is giving very small if any increase in level! Nearly all of my testing has been on a Klipsch Promedia. It has a mini input cable and a aux in jack that can mix inputs. I assumed the input impedance was the same on both, it’s not! Since the mod cable was a mini plug, I plugged into the aux input which has a higher impedance. I was plugging the Dock into the mini input cable which has a lower impedance. When plugging either into the same input, they are nearly the same. Looks like the cable jump will be a convenience item that will not help the car stereos. We will probably have to live with what we have here.
If axon is correct and I think he means the lineout and headphone out share the same signal, than the Fuze is not utilizing the AMS chip lineout pins. If it did, they would be independant signals (externally form the chip due to the dedicated outputs).
Oh well, you have “lineout” cable if you want it, but it looks like you can get nearly the same results out of the headphone jack.