Bluetooth from Ubuntu PC - pops and crackle noise

Volumio Information

Volumio Version: 2.806 (new download & install from yesterday)
Hardware: RPI 3B
DAC: Allo Boss

When playing back audio from desktop PC (running Ubuntu 18.04 with all updates) there is a very noticeable underlying crackling noise in the background. From the Gnome bluetooth menu, it is treating Volumio as a A2DP sink.

There are no visible bluetooth settings in Volumio, is there anything I can do to remove the crackling noise?