i apologize if this may have been covered already, this thread is massive and i'm short on time; please excuse me.

What is DSP?
What is the difference between trunk/console interface and radio interface
This will be installed in an 04 x3 (premium sound) no nav.

I wanted to swap out the headunit, but from research, i don't think the stock amp works without the OEM HU? Would someone please confirm?