Behringer UCA202 - Cubase 6

Hi everyone
I recently purchased a new Mac and found to my annoyance no “stereo in” any more (most of my Cubase use is Scoring and MIDI, and my occasional audio work found the stereo in more than adequate).

I read some reviews and purchased a Behringer UCA202 which works fantastically with Audacity and things like YouTube. A lot of people here seem to use it without issue.

I fired up Cubase 6.5.5 last night and I can’t get it to drive the Behringer.
I have the same symptoms as one other post I saw here (which was Windows, rather than Mac).

On the Mac I can select it in Device Setup, and in VST Connections I can check it has stereo in and out.
But all I get is white noise.
More interestingly, in Apple’s Audio MIDI setup, it becomes marked as Mono, and NOT the default device. If I mark it as stereo, it becomes the default device, and one second later, the Mac’s own stereo is the default device, and the Behringer has become mono again. When I quit Cubase, order is restored to Apple’s Audio MIDI setup.

There are no drivers needed, according to Behringer.

So - any ideas?
Thanks in advance!