As Alex said, active EMGs are just different. I'd say try some Villex pups for the nearest passive equivolent. Otherwise outboard and things like Aguilar Tone Hammer, MXR M-80 D.I.+ or Bassbones may help.
My P sounds great passive and I'm loath to put flats on it as I originally intended as I don't want to change the existing tone. My MXR M-80 gives me a chance to apply some active EQ and that is mostly mids to be honest, that and the passive tone on the bass gives me all I need.