While running version 8.1 on my Mac with the 512 plus interface I tried to also use PreSonus Audiobox USB and not only did it crash ShowXpress but it appears to have corrupted the installation. I had to reinstall 8.1 to get it working again.
When I run Personus Capture on my Persons Studio Live 16.4.2 board that seems to run fine but that is a firewire interface.