The old graph only included standard DSP:

I remeasured it to include Connect+ button effect, and when DSP is off.

This time, I was taking signal from output of an opamp. That is, right before DC-rejection capacitor at power amplifier input. So overall response is for (DC-rejection caps on aux input) + (ADC) + (DSP) + (DAC) + (another cap) + (balanced-to-single-ended-converter circuit), and does not include (yet another cap) + (power amplifier). 

Additionally, I disabled boost converter that powers the amplifier, to reduce noise.

I've also uploaded room-eq-wizard file to the project, so if you want to inspect it, go check it out in project files.

Measuring aux-to-air frequency response remains in to-do list.