Not at all surprised with the results. I’m definitely a fingers first and cabinet second kind of guy.
As far as strings, rounds and flats obviously don't sound the same when fresh. When you keep rounds on for a long time (years), they start sounding more like flats as they lose the zing. I buy most of my basses used so I have no idea what strings are on it unless the seller tells me. I keep them on unless they sound really terrible.
When it’s time to change, I’m not too picky. New rounds? Boomers sound fine to me although they don’t make them with double ball ends so I can’t use them on my Steinberger L2. As time goes on, the number of companies offering double balls is shrinking. So I get whatever I can find. My NS Radius came form the factory with some D’addario rounds. I still use those when I resting it about once a year, saves me thr trouble of having to screw with the intonation setup

I have been using EB Series on my Ps for over 20 years, but when I got my J5 a few years ago it came with TI flats which
feel different due to the tension. They sound pretty much the same to me when I play the basses unplugged.
The most annoying part is when the combination of a so-so pickup with so-so strings, so-so wood and so-so electronics (preamps) comes together for a so-so experience overall. A friend bought a Hartley Benton short-scale P that I've played it at rehearsals and it’s very in your face in an unpleasant way because of weak low end requiring a lot of EQ tweaking to make it usable for me. While the whole is definitely the sum of the cheap parts, it’s impossible for me to tell what needs to be different to make that bass sound better.
All I have to do to reinforce this feeling is to go to GC and start pulling Ps, Js and StingRays of various price levels off the wall. The really cheap stuff sounds and feels the worst, once you get into the middle of the price range the sound is good. The improvements as you head towards the booteek class of FSOs are much more subtle but can be worthwhile. That’s where I agree that it matters to the player but not the audience.
The easiest way to get a major tone improvement?
Switch instruments. Use a P instead of a J or vice versa. The sound that comes out of my Danelectro, my Ps and my Steinberger are hugely different
as they should be since the wood and pickup design and location are so different. When I need upright-like thump, it’s the Dano. When I need super detailed and crisp, it’s the Steinberger. The Ps sit in the middle.