If you use a bypass cap in the attenuation portion. This will tend to equal things out. The lower of the tweeter frequencies are attenuated the full amount and the bypass cap allows (it's values worth) the upper frequencies to pass through the attenuation circuit.

If you do not have a bypass cap in the attenuation circuit. then the whole scale will get pushed down.

When I use an active crossover, and the tweeter need say 12db attenuation. I still use a compensation circuit. It cuts a lot of the hiss from the HF. So for 12 db total, I have a 6db compensation circuit and use the active crossover for the other 6db. This probably isnt as "pure" as using the active xo for the whole 12db as it is designed, but right now this is giving me a good sound.
This is some ball park info and Wayne can give you better details.

Bill