As has been discussed, once I select an Audeze preset Roon uses a headphone icon for the zone icon. This icon remains even if the preset is disabled. There is no obvious way to get rid of it and restore the device icon, such as a Chord Hugo DAC.
Turns out the only way to get rid of the Audeze icon is to remove the Audeze preset from the filter stack.
This is obviously non-discoverable, there is no indication anywhere that making that change in the DSP specification would have that effect in the zone icon. (In my case, I had used the Audeze preset, years ago I stopped using the Audeze headphones in this location, but I continued using other headphones so I didn’t mind the icon. But much later, i rearranged my resources and connected speakers to that DAC, and there was no way I could remove that icon.
It is also inconsistent, nowhere else is the meaning of removing a filter different than disabling it.