Also, if the TRS Aux Ins aren't being used for anything, you can point the AuxIn Remap at 6 preamps too, so X32Rack+SD16+SD8 = 38 preamps. Read more

Unfortuantely you can't mix the LR mix directly to a bus.   As Dave said, using mtxs is an option, but you're limited to only 6 mono monitor sends (or 3 stereo,) because the console only has 6 mtxs.  The mtxs are typically there for when you need to send certain mixes (eg the LR mix) to somewhere else other than the FOH PA, and that other location requires different processing (eq\comp\level\mute) to what the PA does, eg for a recording, overflow, a cry room, a foyer, a camera etc.  If you're already using the mtxs for these purposes, then you have less mtxs to work with for getting LR into IEMs.   Another way to do it (though this has its own caveats) is to mix FOH to a spare stereo subgroup instead of to LR (assign every channel + fx return to the subgroup,) send *only* that subgroup to LR (un-assign all the channels+fx returns from LR so that the only thing in LR is that subgroup,) get 2 spare channels to source their signals from that subgroup (select channel, config tab, 3rd encoder) and mix those 2 channels into your IEM bus. This requires 2 spare buses and 2 spare channels, but it gives you the capacity to mix LR into all your monitors, not just 6x mono\3x stereo which is the limit imposed using the mtx solution   Of course there's always the analogue-loopback option, but on a digital console that can mean delay issues.   The only other way I can think of doing it on the X32 is to essentially sacrifice the solo bus; solo LR+the IEM bus at the same time, and send the solo bus down to the S32 to feed the headphone amp.  However while this can work if you've used all your mtxs\buses\channels for other things (meaning the first 2 solutions are off the table,) this still works best with a spare matrix, it only works for 1 monitor send, and it means you can't solo anything else, otherwise whoever's listening to the IEM will get a surprise.   Edit: If the person wants LR in their IEM mix because they're feeling isolated, want to vibe off the PA etc, then a room mic on a spare channel mixed into their IEM mix can help. Read more