That then falls back to style vs. tone.
Tone is the sound the instrument; and in the case of a guitar\bass all of the electronics that go along with it. Because of the several layers between the player and the sound the audience is hearing, you can't compare an acoustic instrument like a wood wind or brass to an electric bass. Even a piano or something like a violin or double bass is a stretch.
No player will make a passive P with flats sound like Warwick Thumb. That's tone. And it's literally impossible. Physics won't allow it. People confuse style or character for tone.
And yes, a rubbish bass rig will make the greatest player sound bad. Again, physics.
No. Anyone can say things like "because physics," that doesn't win you an argument on the internet or anywhere else. You should read up on the physics of timbre.
First of all, as was clarified earlier in the thread, we're referring to timbre. Tone is the amount of bass or treble frequencies controlled in or out of a signal via EQ or capacitors. If we can agree that for purposes of this discussion though tone=timbre, fine, let's do that.
Second of all, every individual instrument has it's own timbre. Of course no player is going to make a P bass sound like a Warwick, or a tuba, or a lute. Can we just accept that and not bring it up again, because it's a stupid derail at best. Clearly Jimmy was not suggesting that a saxophone sounds like a bass guitar, or that a P bass sounds like a Warwick Thumb.
Style and embouchure are both aspects of technique, but they are not synonyms - and embouchure definitely affects timbre, whether a note is amplified and played through a series of gain stages or played and heard acoustically. If you strike the strings hard, you will create more harmonics in your signal than if you strike the string softly, which is exactly what timbre is - a difference in timbre is the difference in the number of harmonic frequencies in the signal, which harmonic frequencies are present in the signal, and how strong each of those harmonics is. It isn't just style or technique either - have the same person play the same passage on the same bass with three different pick gauges from the same pick manufacturer. Same style, same technique, same player - different quality of "meat" hitting the strings. Just like differences in pick thicknesses, there are differences in fingers - how much skin is on the finger, how much muscle is between the finger and the bone, how wide or narrow those fingers are and whether they are fretting the string or plucking the string. Wide fingers fretting strings will sound different from narrow fingers fretting strings. Can I tell you what those differences are? Hell no. But there are reasons that have nothing to do with the electrical components in a signal chain for why Miles sounds very different from Louis (who were both microphoned and amplified, at least on every recording of them that I've heard) even though they both played trumpet. Those differences are mostly their embouchure, since you can hear the same differences throughout their careers. Same as Jamerson and Geezer Butler. They sound very different, even though they're both playing equipment that is far more alike than it is different - they're not playing Warwicks, anyway. They both sound like P basses with flats, and they're both playing near the neck, but they're both recognizably different from each other throughout their careers, and recognizably themselves throughout their careers. Their "tone" is different, their timbre is different. They strike the strings different, with their very own fingers, nobody else's.
I don't agree all tone is in the fingers - but the fingers are definitely a contributor to good or bad tone, as is gear, and what is meant by saying "tone is in the fingers" is really just "don't worry about your gear, go and practice." Because most of us spend way too much time obsessing over our gear instead of practicing.