Hercules RMX2 & Djay for Mac - routing external sources through software?

I’m using an RMX2 with my Mac to play tunes - the midi mapping that’s available seems to work for most things.

However, can I utilise the line level auxiliary sources? Pressing the source button on the console has no function. Is there anyway of enabling it?

The reason I ask is that I’ve a private gig coming up and would like to use the RMX as the sole interface between my tunes and the p.a. BUT I could really use the ability of DJAY on my iPhone and its spotify integration for those tunes that I don’t have. Therefore I want to be able to switch between a deck on the Mac and that of the iPhone plugged in via the external input.

It’s bloomin’ great that spotify is integrated like that in the iOS version - hurry up and implement it in the Mac version please!