L322 DSP problems

I would really appreciate some help. I have a 2003 autobiography, with (according to Landrover) a DSP unit fitted as standard. It happens to have a more recent DVD sat nav, and CD changer and DVD player serving the headrests...and all works reasonably well, but I get occasional added base, not in time with music, almost like interference, especially on the M25. It happened abroad too during august. So, I started to look at the manual and that led me to the DSP settings on screen but there aren't any??. Infact DSP isnt even an option on the menu screen. I took it to a Landrover specialist for a service and asked him to have a quick look, but he didnt have time to dig around in the boot, but he pointed to what he thought was the DSP unit. I have checked all the wires and everything seems fine. He called Landrover and quoted the chassis number, and mine left the factory with DSP, but its not present on the display.
Ive found a picture of a DSP unit on eBay, but I cannot see it in my boot. Is it fitted out of view, behind the subwoofer, as I have not yet taken the trim away to expose the sub yet. If the car has a DSP and the audio works, where have the settings gone in my menu?
Very much appreciated if someone knows what I am talking about.

Looks like a kind eBayer may have provided the answer. The Autobiography came with Logic 7 not, DSP....so that explains all. Just need to sort out my odd sound problems now.
cheers