Accessories Car charger without EMI?

[overclock]

I have a couple of car chargers with the micro usb plug. One is the Sprint Rugged and a cheap knockoff from ebay. I connect my Evo to my car stereo using a 3.5mm aux jack. When I have the charger connected I get a great deal of EMI coming thru the speakers. There is less with the Sprint Rugged than the cheap Chinese one but the EMI is still there, an noticeable.

Is there a car charger of top quality that won't add to the EMI?

Thanks!

 

[Stepintothedark]

Do you have a factory radio? sounds to me like a grounding issue with the 12v port

 

[overclock]

I do have a factory radio. It is actually impossible to change the head unit in my vehicle. The dash design and the fact that nobody makes an adapter. I have two plugs, one for the cigarette lighter and another for aux items. I'll try both and see if one is better grounded than another.