I have flats on my Alembic, and it’s my “fanciest” bass. It’s the one in my avatar. I use them because I prefer the feel and sound of flat wounds on all my basses.
I have rounds on my Modulus and do not have flats on my Alembic. But the Alembic is fretless, nevertheless came with rounds. Only they like instantly began chewing the fingerboard and I freaked out! Flats are not quite the thing for that bass so I put ground wounds on it which it still has. Same for my G&L fretless L2500 which came (used) with ground wounds and I've left them on it. My fretted L2500 has rounds on it. SX 6 string Fretless Fender clone in avatar, however, does have flats on it. I guess that doesn't qualify as a "fancy" bass! And it's also not active, but I will say that each and every of these basses is killer in it's own way. I also have two other identical SX 6 string fretted basses and one has flats and one has rounds. Strings make a huge difference in sound even on identical basses. My Squier P-bass 5 has flats but is passive. I'm trying to think if ANY of my active basses have flats and I don't think they do!

