Thanks a lot for your replies guys. Even though barely understood them! I will try to read up to understand completely what you mean.
So basically I'd have a cable going from Aux Send into a smartphone or other recorder?
But again, isn't there a problem of getting the signal from the L/R channels of the 3.5mm pin to the third MIC channel?
If it stays in the L/R channel (ie, first 2 lines on the 3.5mm pin), then I guess I'd be stuck with using a handheld recorder, not a smartphone?