Thanks, MightyBoo. It seems the headroom for some (but not all) USB DACs is calculated differently from 0dBFS reference used inside Core Audio. We are still investigating this.
In the meantime, if you want to use speaker profiles with DPS HEAR engaged, copy the profile from Mac HD/Library/Application Support/Bongiovi Acoustics/External Speakers to ../../../../../Headphones. All profiles in the Headphones folder will show up in the Headphones profile drop down menu and may have HEAR engaged.