rmbg, unfortunately I can't offer anything constructive here, only that with my 950, the bass is one of the best features. I previously had a Kinergetics/Chiro pre-pro, so this 950 replaces some pretty good company. Either you:
A. Have a defective unit
B. Have a faulty set-up
C. Have some other defective piece (amp, speakers, etc.
There is no reason you have to use a separate preamp to get your bass. Recheck your setup, maybe contact Outlaw for a replacement unit.
Mike