Volume control when connected to miniDSP Flex

Hi all,

I'm hoping that this is possible - I have a Macbook Air M2 (2022) that I will occasionally have connected to a miniDSP Flex (that I use as a preamp in my 2.1 HT system). The MBA's use case is mainly as the engine to using Room EQ Wizard (REW), the miniDSP DC software, web browser, and digital music hub. When I have the MBA connected, what I am hoping to achieve is the MBA "relinquishing" volume control to the Flex (i.e. when/if I press the volume -/+ on the keyboard shows the speaker icon with the circle w/line through it).

I kind of know it's possible because with my Mac Mini M1 desktop system, I have an external DAC (Topping E50), Headphone amp (Topping L50) and amplifier (Topping PA3s), and with the DAC connected, the volume control moves to either my L50 or my PA3s (pressing the volume keys on the keyboard shows the speaker icon with the circle w/line through it).

Is there a sound option I have simply overlooked or is there no possible way to have that functionality with the MBA and Flex?

Thanks in advance!