Delphi TNR800, DVD and amplifier?

Hi,
I have a 2006 Hummer H2 with the stock navi system installed (TNR800).
I also have the factory DVD-system mounted.
 
To my suprice the factory mounted DVD-system use a small frequency transmitter instead of a direct line to the TNR800 = poor sound quality! Is there any way of connecting the DVD directly to the TNR800?
 
Also, have anyone tried to connect an extra amplifier to the TNR800? Does it have pre-amp outputs (for RCA cables) or is there any other way to connect an active subwoofer to the TNR800?
 
Thanks
Peter