[br]Check out Alien Ears, or you can go for Westones have a large soundstage very suitable for distinguishing the instruments in the acoustic space.

I have a Shure PSM200 and run the guitar on one and the other bands in the other, as I had an ear surgery.

Take a look at other forums/sites like Stereophile and SoundMaximum

Go for wired IEMs, as they do have more fidelity.

For presonus 16.4.2, I suggest you go with multi-channel IEMs as musicians will have more control over what they hear from their monitors.