I contacted Support and they reiterated the sample rate solution ...
"please try with 16bit/48 Khz as a workaround until a new driver is released​"
I can report this does work.
What I'd failed to spot previously was, when pressing the test button on this setting, I still get an error, but it has changed to "The device is in use by another application...."
It does then play the left\right test sample and works OK in Pod Farm.
Support also pointed out there is a 2.59 update of Pod farm to install.
Thanks Support :)
James