I do this with my Genos when playing at church. Lately I’ve had to sit away from the congregation, with my main PAS speaker system some distance from me. I’m using a iLoud active speaker from IK multmedia as a personal monitor near me when playing. I connect my main Yamaha PAS active speaker system to the main line outputs of the Genos, and connect my iLoud monitor speaker to the Aux out (Sub 3 and 4) jacks. I’ve adjusted the settings on Genos to feed the main L/R signal to both the main outputs AND the sub 3/4 outputs. The only downside though is the sub 3/4 outputs are at fixed volume, so not controlled by the master volume control on the Genos. Not too much of an issue as my iLoud active speaker has it’s own volume control, but it would have been nice if there was an option to adjust both sets of outs via the volume master on Genos. I’m guessing it’s similar with Tyros 5. I might however just make a pair of splitters so I can connect both sets of speakers to the main outputs. Given they are just line level signals, I’m sure it won’t be a problem. Another option would be to use the headphone output to drive one set of speakers - a bit noisier but gives the advantage of both being controllable from the master volume.
Simon