I know, it is kind of lame. But I never really thought about the settings being adjustable volume-wise. Your analogy is quite apt. I have often switched to parallel, and said, nah that's kind of weak and lacked phatness. I never really said, let me play with this setting and try to get a good tone from it in its own right.This is an interesting observation. Now I'm wondering how much of the series sound I love is related to the perceived boost in volume alone. Almost like it's tough going 35 after youve been flying down the highway. Might be worth it to spend some time in parallel.
Now, on a different bass, I might play it on series rather than parallel. Not trying to say that series is a bad setting. But for my ABZ, to my ear, it is the sweet spot. I never would have figured that out had I not left it in parallel, and started playing around with it as if it were in series. Really weird! Also, it took my palette a while to really get that setting. But now that I have, I LOVE it! It absolutely kills in a mix, and my band is doing lots of heavier rock. Very tight. Very controlled low end, but growly and incredibly clear and phat in the mix. And when I'm playing on the D and G, I don't cringe, I smile.
IIRC, Sheldon was opining that the current SJ with the FD3's in the 'sixties positions' copped the vintage tone better than SJ's with fatties in the 'seventies positions'. That is the only comparison that I have heard.