For those of you who have a series/parallel switch on your bass, I'd like to hear your description of the difference you hear in the resulting sound that occurs from the switching. Accompanied/unaccompanied, active/passive, eq'd/not, fretted/fretless, other variables - doesn't really matter at this point. But if you want to add details fine.
From my experience, thicker sound with series engaged. Fairly similar to the usual difference between series/parallel on an individual pickup, with a bit more boom. I generally prefer to use a pick with master series/parallel, the finger sound can be a bit boomy otherwise IME.
I have my MIM-P set for series/parallel switching on the DP146 pickup. The parallel mode is noticeably different. The tone is more clear and bell-like, with a reduced loudness. It is not unusable at all, just different.