I have only owned the ADI-2 DAC FS for a couple of weeks, so forgive me if I am misunderstanding something.

There are at least three ways to enable/disable the EQ function:

(1) The menu control on the ADI-2, at EQ > EQ Enable / Presets > EQ Enable [On or Off, changed by encoder 2]

(2) The control in the ADI-2 Remote app, at (source) > Parametric EQ [On or Off, changed by the virtual slider switch]

(3) The EQ button on the hardware remote

Ideally, a change in any of these controls should be equivalent, and reflected in the user interface states of the ADI-2 and ADI-2 Remote. This is true when I use (1) or (3). When I toggle the Parametric EQ control in the ADI-2 Remote app (2), the FR curves go grey or colored on both ADI-2 and ADI-2 Remote. But the EQ Enable control in the ADI-2 (1) does not change. This seems like a UI bug.

I am not sure how the Listen button in the ADI-2 Remote EQ Preset Editor interacts with, or overrides, the EQ Enable controls. But perhaps that's a topic for a different thread.