How to equalize a bi-amplification setup?


Greetings!

Any one experienced in bi-amplification setups with different amplifiers, where output must be equalized?

In my bi-amp setup I use one pre-amplifier connected two different amplifiers, via balanced and unbalanced connection, feeding a pair of 2-ways loudspeakers (Pass Aleph P, Pass Aleph 3 on tweeter and Pass Aleph 0s on woofer).

Problem is the Aleph 0s results in a final higher sound volume (at least +3dB). Theorically I think this should not happen as manual gain of both amplifiers indicate a +20dB gain, altough the Aleph 0s outputs much more current.

How can I "calm down" the bass amp without comprimising the sound quality and without opening the loudspeaker to introduce one attenuation circuit?
sony
From Nelson Pass I received an excellent tip that applies to this or other setup:

Connecting preamplifier balanced output to the amplifiers unbalanced inputs: pin 3 for Amp1, pin 2 for Amp2; both share pin 1 ground; phase of amp1 inverted at the speaker output.

If Amp1 has more gain than amp2, put pin 3 into a 10K pot.

Voila! Simple and brilliant.
Have you look into an active crossover? Multi-amp system really need an active crossover to be done correctly.