It would be nice to have an on screen EQ with aftermarket gear.
It is possible but its really expensive to do. How often do you acually change your EQ settings anyway?
Personally I've only adjusted mine once when I first bought my X.

What I'm getting to is IMO its not worth it to keep the DSP.
If you absolutely stuck on DSP take a look at these two products.
http://www.alpine-usa.com/en/product...model=PXE-H650
http://www.alpine-usa.com/en/product...model=VPA-B222

BTW.... All the Rockford stuff I've installed hasn't impressed me at all(except there high end subs).
Years ago Rockford made CD players and EQ's. You have to wonder why they stopped making them.
hint....poor quality and could never be repaired(always had to be replaced)