Metrum HEX DAC - OS Sierra drivers

Have had this device since 2014 which is connected via a USB port

Upon loading OS Sierra, the device is no longer recognised. The factory tell me they are unable to produce a new driver (this is the actual message from them: Apple is not giving any data about changes in their system so it is impossible to create new drivers.)

The same thing occurred in 2015 with a KORG device, it took Apple 7 months to approve a driver which Korg submitted the day after El Capitan was released

Why is there this hold up? The METRUM factory tell me that they get no response to their enquiries?

I don't really want to change to a Windows computer, but will have to unless this is sorted

Thank you