I have the pioneer avh 4200 installed in my car, I had my Ipod touch gen 2 connected to the ipod input, just last night I plugged in my new iphone 4 and played the same songs. I noticed the iphone 4 sounds better on the stock bose system, where the ipod touch doesn't sound as good can not turn the volume as higher on the same songs. Did some testing but does anyone know if the iphone 4 has better audio output from its port that makes the system sound better?

 

I noticed the difference too..I used to play my Ipod 30gb using the USA spec adaptor and stock BOSE speakers and HU. When I tried my Iphone 4, I notice an improvement in sound quality..

It is probably the phone..

 

maybe there's a difference in output voltage from the ipod/iphone. when i replaced my old 2nd gen ipod mini with a 5th gen mini, i noticed that i had to turn up the volume much higher to get the same sound level (still using bose HU and usa spec ipod adapter). perhaps the opposite is true going from ipods to the iphone

 

My other car has a factory hook up for an iPod/iPhone (no blue-tooth streaming) so I have to use the hook up with that one. One thing that is nice is your can control the iPhone from the controls on the steering wheel but one that that drives me nuts, is when you have you iPhone connected this way, it just displays "Accessory connected" and you can not change the music manually on the iPhone and you are forced to use the Stereo which can be quite a pain scrolling through long lists before getting to the right one. Many times I will get frustrated, unplug the iPhone, select the music I want to play, and then plug it back in.

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