This can be done in TotalMix using its internal loopback feature, but the method consumes an additional pair of inputs and outputs, and has its own defects. Assign your DAW main outputs to an unused pair of RME outputs, then turn on loopback for those outputs and route them to an unused pair of inputs, then assign those inputs to the plugin host of your choice (I've used Blue Cat Patchwork for this successfully), then assign the plugin host's outputs to your monitors. (I'm describing this from memory, I hope it's reasonably clear.) In addition to being cumbersome, this has another disadvantage, at least using ASIO drivers on Windows. Every time you switch DAWs, you have to restart the plugin host containing Ref3. That's a side effect of the way ASIO works. But Soundworks now provides another way. The Systemwide version of Reference 3 is now available (I think the price is $59). It's limitation -- which is fatal for purposes of this discussion -- is that the Windows version doesn't support ASIO. I doubt that anyone in this forum uses anything but ASIO.