I've got a kludge of 3 setups I use, and I swap the pieces around depending on what I feel like carrying around. For preamps, I have a custom 2-channel dual-showman-ish tube unit with an integrated power supply for the bass, an ART tube preamp with parametric eq and compression (I love the sound of this unit), and a Line 6 Bass Pod Pro. The Bass Pod Pro sounds great, but could use a low-range parametric and has been back to the factory for problems twice in one year, so I haven't used it nearly as much as the others. For power, I have a couple of ancient (at least 40 years old) 200 watt mono Bogen industrial tube amps and a Peavey DECA 1200. The Bogens sound incredible! The Peavey sounds good too. I have no complaints there. I use an Ashley X-over when I choose to biamp, and a cheap Alesis stereo compressor (3630 I think) after the X-over to run different ratios on the highs and lows. Sometimes I also run the signals through a BBE. Oh, and I have an old Peavey Mark III bass head that has literally been under water, but it works. For cabinets, I have an old Lab Series 1-15, and Dr. Fong 1-18 with a Peavey Black Widow in it, a couple of 2-10 cabinets and a MusicMan 4-12 loaded with Black Widows (very, very heavy). I mix and match depending on venue/genre/weight. The Dr. Fong puts out the deepest bass, the 4-12 really punches and I can lift the Lab Series. Mostly I let the P.A. do the work. People who have never played with a big PA doing the work (and a good FOH engineer) don't know what they are missing. I love the sound of the bass coming back at me from the front, especially the ringing lows...
I once designed and built a 2-18 isobaric cabinet which put out the absolute deepest bass I've ever felt, but my soundman made me stop using it because it put out too much really, really deep bass... :-(
john