Long version:
When playing in the car, I had a little wondered why both my iPod Touch 2G (8GB), as well as my iPod Touch 3G (64GB) and iPod Classic 6G (160GB) light when playing quiet passages, but had nevertheless very annoying background noises , always when the iPod is loaded at the same time in the car. The higher the power consumption was (display brightness), the louder were the disturbing noises.
At first I had my USB charger from Belkin is suspected ("shoddy" output voltage, ground offset with radio) and so I built his own charger, which also has 100% electrical isolation (DC / DC switching converter). The output voltage was then clean and Floating, noises were still there. So there was only the cable left, because the chance that three iPods are bad designed and / or are defective, but is then very low.
So open the welded Dock connector of the cable and have the errors I noticed: there are two ground points together. GND GND for control and for Line Out. Although the connections idle have identical potential, has one of the two pins in current flow (loading) a slight offset, which is responsible for the noise. Mass is just not the same mass.
The connection between the two mass points (pins 1 and 2) separate (pin 1 is GND for the controller, Pin 2 is GND for line out), and even the cable does exactly what it should, and the disturbing noises are gone.
Conclusion:
Here obviously have some developers "tinkered", who have no idea of electronics. Who to sound not much emphasis (or on noise loading), or who like himself lends a hand, the cable be recommended. For the rest: Stay away !!!
Another tip:
Who wants to use the cable car and has anyway opened the plug, which I can recommend to built 68 kOhm resistance to 1MOhm exchange resistance. This gives the iPod an additional feature, namely it pauses when the ignition is switched off (provided the ignition switches the USB loader and the iPod in the car always depends on the charger), and you do not always think of off.
