Ckorody,
Please don't take offence, but you are using an incorrect term - that port is not a USB socket. It's the proprietary "Apple dock". Otherwise, you are correct about the mini-plug being after the headphone op amp and volume control. There are only three pins in the Apple dock that are required for audio - Left, Right and Ground. You can rip the rest out - it makes it easier to solder inside.
Regards,
Please don't take offence, but you are using an incorrect term - that port is not a USB socket. It's the proprietary "Apple dock". Otherwise, you are correct about the mini-plug being after the headphone op amp and volume control. There are only three pins in the Apple dock that are required for audio - Left, Right and Ground. You can rip the rest out - it makes it easier to solder inside.
Regards,