tldr: Mesa Subway and GK RB, but you have to also have a Wal bass for the GK.
what is "the other" thing you should have?
so, like, a different kind of non-linear-dynamics and slightly dirty eq sorta lo-fi thing for recording or playing cool shows for cool people?
Maybe a pre-CBS Bassman? Whatever GK RB that Flea used in the 90s?
As far as distinct tones/voicing… Not
not an amp, kinda- a proper solid top DB? Markbass will always stick out in my mind as having a very distinct sound. Hartke with aluminum speakers also was pretty distinct sounding.
I don't think any of these are Should Have's for a bassist to own, but are definitely Pretty Cool for a recording studio to have.
I love my old Fliptop, I even love it when I borrow or temporarily own an active bass to run through it, but rarely do I seriously suggest that it's something that any bassist
should own.
Despite the raving reviews I've read about Aguilar, Eden, SWR, Trace, Genz, Mesa, and others- my ears aren't developed enough to hear any significant difference between them. They're all great at reproducing what's put into them; they're great at being professional bass guitar amplifiers.
If I were trying to be changing my profession to studio/live bass guitarist for hire, I'd keep my Flip at home and just get a WD800 & matching pair of 215's as my work rig.
Eventually, a Wal and a GK RB rig would dispose of some income at least temporarily but I'd almost definitely only play BSSM songs on that setup.