Stereo system noise from using phone/dock/charger

So, I've been getting some noise when using my phone for an audio source.

I have a car dock for my phone that has a micro-usb that slides into the phone for audio and charging. The dock has a micro usb plug on the back as well as a 3.5mm outlet.

I have a 3.5mm cable (just a cheap one I had laying around) that goes from the car dock to the aux input of the WS420SQ.

I also have a car charger going into the car dock's micro usb.


I would get noise on my system (like the same kind of sound speakers make when they are getting GSM interference). So I tried unplugging the 3.5mm cable from the car dock and plugged it directly into the headphone jack of the phone. That seemed to help on last weekend's trip.

Yesterday I was getting noise in my system again and the "solution" was to unplug the car charger (which was plugged into one of the boat's 12v cig lighter style sockets).

I've heard that there's some "ground loop" stuff going on. I'm curious what's going to be the best way to address this.

I'd like to still use the car dock if possible, because it's nice to have something holding my phone as I'm driving and to still have the ability to change songs and stuff (rather than keep it inaccessible in the glovebox).

I am not opposed to hard wiring the car charger into the boat's electrical system (although I'm open to hearing the best place to tap the power for that).

I'm certainly willing to buy a different 3.5mm cable to connect my dock or phone to the WS420SQ.

Thanks for the insight.