Equalizing Bi-Amp outputs

I need help configuring a inline "equalizer" Evidently, the RCA out of the DAC is 4 db and the XLR is 14 db. I'm bi-amping my speakers that are Bi-wired, so my tweeter and mid range use a separate crossover from the woofers. The input sensitivity is the same for both amps. Obviously, the volume from the woofers is much louder than the volume from the tweeter/midrange  because of the mismatched outputs from the DAC. I've investigated putting an attenuator or a potentiometer in line from the DAC, but Von Schweikert recommends a simple device inline from the "source=> xlr cable=>equalizer => amp". I have the specs from both amps, DAC and speakers.

Does anybody have a the formula or knows what parts I will need to build this thing so the input voltage to both amps will be the same?