What you can and cannot do is somewhat determined by your computer type and operating system. Unfortunately, the MODX drivers, for PC at least, do not let you choose MODX's Digital Input as a destination for the main system audio. I can route main system audio out to Main L&R from the computer. This path does not come back to Cubase. Only Digital L&R can. In order to get around this - I've used either 3rd party "drivers" to redirect audio in ways the Yamaha Steinberg USB Driver doesn't let you - or I've also uninstalled the drivers altogether which allows for a little more control only for the PC's main speaker output back to MODX using the class compliant drivers. I imagine there are more or different options on Mac.

The easiest thing to do, really, is to get a 2nd machine to be your "spotify" (backing track) playing machine. Connect it up using analog connections to the A/D input. The A/D input will route to the digital output of MODX and Cubase will pick this up. You can use an audio interface on the 2nd backing-track machine so the audio output is higher fidelity than a 3.5mm consumer-grade output.

In this configuration, you would set the A/D output to Main L&R so you can hear the backing track and record it at the same time. Everything will go to Main L&R so the backing and what you play will be mixed on the same audio channel.

If you want to split the channels - you could use the same connect to A/D input. Again set the A/D input's output to Main L&R. However, set all of your Part outputs to USB channels other than Main L&R. Make sure "Direct Monitor" is turned on under [UTILITY] "Settings" -> "Audio I/O". This way you will hear everything mixed on your monitor speakers and your backing track + MODX tone generator will send out to different audio (USB) channels so they can be recorded on separate audio tracks.

Thanks Jason,

So I can have 2 audio interfaces and drivers running at the same time on the one computer?

One driver works with the MODX and the other works with my 2nd separate audio interface?

Sounds interesting and I might try it but also sounds like it may be simpler to try to get the original audio files that I am listening to through Spotify... I know the artist but he is not techie and has trouble sending files, etc....

I didn't suggest that - but you can try.