I've said it before that I like the A Designs mic preamp DI for big bass sound. It's fairly clean but its big in the monitors and tight at the same time.
One of the other Gear Slutz members helped design or test the A Designs REDDI (as in "red DI") and reports its the best bass DI ever (or some other sort of big statement like it). I'd tend to believe it given the nice bass image from their preamps. I don't know when the REDDI is coming out. But, I'd keep it in mind.
Steve
www.mojopie.com