Thanks for the replies everyone, I'm the same I see the meters bouncing on PT then about a second later they bounce on the physical device. Asio4All does completely fix the problem, but then I can't use Basehead at the same time so it's pretty useless to me in my workflow. I've got Sound Devices back to the drawing board though so that's good. Cheers everyone!
Is anyone on here using/has used the USBPre 2 usb interface? I've been having strange problems since I got it relating to Pro Tools. It's a strange occasional audio delay, the timeline cursor will move then I'll hear audio about a second later. The video engine also crashes whilst this is happening. This is my second unit as the first one was replaced on warranty. I've done everything under the sun to try and remedy it to no avail. My theory is it's a driver issue (I'm on windows 10). Of course I've been dealing with Sound Devices support for a while now but they're stumped too.