Get spectrum data from specific Audio Mixer?

Is there a way to get the spectrum data of a specific mixer rather than the audio listener?

I need ambient audio to be playing that is separate from the audio being used for visualization.

I’ve got visualization working for both audio sources and the audio listener, but I want to visualize a layered soundscape separate from the ambient audio.

I need something similar. I want to put several sounds into a mixer and then visualize those sounds together, rather than each AudioSource individually.

Has anyone found a solution to this yet?