Finding "that sound" has got to be one of the hardest things for a bass player to do. I've got a few amps in mind, but nothing definite. What I'm considering:
Gallien-Krueger 2001RB: I had one of these for a while, but its rather short lifespan came to a close at the expense of a bright blue flash and a lot of smoke out of the front grill. It sounded great in my bedroom, but I never got to play it with the band.
Sansamp RBI + power amp: I like the tone of these setups, but I think they have a tendency (based on the BDDI) to get lost in the mix when doing anything in the upper register, particularily on the D and G strings.
Ampeg SVT-6 Pro: I normally am not a fan of the Ampeg sound, but I rather like the tone of the 3 Pro. The problem there is the rather weak output of the 3 Pro. Well, the 6 Pro is supposedly a similar tone but in a more powerful package, and with 6 preamp tubes (yikes), an adjustable tube voltage (I'm guessing this effects the gain and saturation of the tubes), plus compression and a parametric EQ section.