I'm with you on the Darkglass sound; to me it sounds like a comb and bog roll, but I think it may fit into the mix well.
A real Ampeg is probably the answer (to most bass sound questions), but lugging one of those around is a chore.
My Stomp is good for incidental effects, but I wouldn't use it on all the time; in face I even switch mine out via a looper, as it affects the sound even with everything off.
I've got Ampeg, SWR, Trace, and RBI preamps, but I've not spent much time with them as my Markbass EVO's emulation is really good; I took some to a Bass Bash, but the Markbass sounded good and I never got round to turning them on.