please explain how the apple route sucks... i have an iphone 4 and the quality from it is great. via usb.
I have a iPhone 4 and pioneer AVH-5200. I use the USB cable. I have songs in 720+Kbps in apple lossless format. There is a huge audible difference between playing from the iPhone, USB drive, sd card, and cd. Maybe my speakers just make it more noticeable on the fine details some speakers to reproduce as easily. It's extra background noise and scratchiness in voices and instruments that are the most noticeable.
In my setup, There's no real audible difference between a CD and a good WAV or apple lossless rip. But then again I'm running 4 Fosgate prime tweeters and 2 prime 6.5s hooked up to a Fosgate 300.4, so I'm not exactly set up for extremely crisp sq.