Audio Playback Issues with Final Cut Pro X

We have the latest 27 inch iMac 5K Retina with 8GB of RAM. Running Sierra 10.12.6. We installed an Intensity Shuttle USB3 to provide output to an Eizo HD monitor and audio out to a small notepad mixer connected to Genelec speakers. When using FCPX 10.4 Video playback via HDMI is fine but the phono audio output from the Shuttle is distorted and crackly with digital artifacts.

When we playback from Media Express the sound and picture are both OK.

We have FCPX settings all correct with the A/V Output set to the Blackmagic device.

Any ideas on what could be causing this? We are using the latest Video Desktop Drivers for Mac 10.9.10

TIA

I've had the smae issues on the UltraStudio express for quite some time. The only driver I've found that works with audio is the 10.7.1 driver. But you're losing some of the video improvement to the driver too. Been hoping they'd address this for years now and they haven't. Don't knwo if there's a good bug reporting mechanism.