[quote name='kyboo' timestamp='1409314700' post='2538564']
It also depends where the cable from the bass goes, and how long it goes. Active preamps buffer pickups from the chain, meaning there is no interaction between a cable, the first pedal and pickups. That is not the case with passive basses. Try to use a quite long cable, you might hear the difference then. High frequencies will be very likely attenuated.
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It's definitely affected by impedance. Running into a mixer's line in (20Kohm) there's a distinct loss of top end in passive mode - as you'd expect.