The filters do have an audible effect even with the minutest tweak of them It's very subtle and enables you to really fine tune the sound. I found that much more evident when I upgraded my bass rig to something more hi-fi than my small Trace Elliot combo. Now I have a rig that is very popular here amongst forum members, F-1X, SF-2 and QSC Power amp, and everything is audible in amazing clarity.
The sound I tend to prefer is to have the neck pick up filter rolled all the way back anti-clockwise, Q-switch off, bridge filter about 3/4 of the way open.
Then with the pickup blend knob at the neck pickup end and the bridge q-switch on, I wind the blend pot open towards the bridge just till you can hear the bite of the bridge pickup.
Then I turn the bridge filter off for general playing and back on when playing melody or need a bit of bite.
Thats the sound I start with and depending on the track I'm doing i move from there.
Time spent experimenting is worth it when it comes to getting on-stage.
It's worth remembering as mica said before, the Q-switch affects mainly the attack portion of the note.
Jazzyvee