You don't need any "system", just use any headphone or ear-plug that is available for you, What you will need is a headhphone amplifier like the HP4 or HP60 fom PreSonus. Then connect Mon1 and Mon2 of your AR16 to the left/right inputs of the headphone amp, and that's all you need to do. Now you can create a stereo/left & right mix for all band members and get to know "in-ear monitoring".

You will see very soon that the AR16 is too limited for advanced in-ear monitoring. You will need a stereo mix for each (!) band member, so if your band has five members, you will need a mixer with 10 aux mixes to create five stereo mixes. The SL 32SC/SL 16 consoles or the 24R rack mixer of Series III would be able to deliver this, and they do have much more features than the AR mixers have. For example, they have four effect slots (for several effects) and you can send FX to the aux/in-ear mixes...

But try the "stereo mix for all"-project first. You will get an idea how in-ear monitoring sounds and what it can do for you. Then plan the next step.