The current version of DPS for Mac is 18.104.22.168. You may wish to uninstall DPS using the uninstaller found in Applications -> Bongiovi DPS, then restart your computer. Then reinstall DPS from fresh installation media from bongiovidps.com/download.
Please let me know if you have any further difficulty.
I dont have that type of computer. However what you want is for the application feeding DPS to be at 100%. Then use system / computer main volume to control level from DPS to a desired level for your speakers.