The iSimple media gateway will use your steering wheel controls for anything that is plugged into the gateway that is digital (ipod connection, or bluetooth). I can't tell any quality difference between the bluetooth and using the aux cable except the aux cable has higher volume at a lower setting. I am using factory bose though so maybe it just cant replicate the distortion
I usually keep the volume on the ipad all the way to max minus 1 and listen to the radio at 15 on the radio. ive put the radio to the max of 30 and it still sounds great but its too loud unless you like that sort of thing.