One bass, plus knob twiddling, plus in my case a Line 6 Pod XT Live. With careful patch setting-up, I can get smooth Marcus slap, warm Jamerson woof, Bruce à la Badge, My Generation JAE, you name it. The versatility is incredible and I highly recommend it for live work if you need a wide tonal variety of the type you describe.
I just wish I could play as well as these guys too