nickE60M5

I purchased a brand new BMW Y-adapter to plug my iPhone 6s and now XR into the center console audio jacks to play music via USB/AUX. When I do this the sound quality is very poor and there is distortion to the point where I initially thought a had blown the speakers. I put a CD in and it sounds great, no blown speakers. Any thoughts on why this is? Do I need the old Y-adapter that has the 30pin instead of the lightning end? I own a 30 pin to lightning adapter I could use for this. Would this solve this since the adapter would be more relevant to car (2010)?