Mbox 3 mini and Pro Tools 11

[sammarshallmusic]

Having issues using my Mbox 3 with Pro Tools 11. Getting hardware buffer errors while my CPU usage is way below 20%. When I use the built in line output it works fine but there is too much noise from the cable to work with. It will only use the mbox with the aggregate device and tells me that is unable to run at 48k with just the mbox alone. Has anyone come across this issue? Thanks so much!