No sound through headphones when playing audio though HDMI instead of RCA

So everything works completely fine when i play through an RCA cable to a speaker, but ive moved my decks into a different room and im playing through a HDMI cable, initially i couldnt get any sound when playing through DDJ400 line, but i changed that to Denon AVR which is what the HDMI is plugged into and sound works perfectly, decks work fine, but now nothing comes out of my headphones when i press cue and songs are playing, ive been playing around with the settings and if i get it so that music comes out of the headphones it means i sacrifice any music coming out of the speakers, so i cant win at the moment, im really stuck, thanks for any help.

Dan