Been doing more research and I think I am gonna try out the Phenyx Pro PTM 10 IEM system.
It is a stereo wireless system at about $220 for receiver, transmitter, and crappy buds. Reviews claim decent low frequency performance and decent stereo separation, for the money.
I still was hoping to get some feedback from yall about stereo IEM vs mono. For example, on some fixed budget, would you prioritize mono if that meant each band member could have their own mix, or stereo except everyone got the same mix or perhaps there were only two different mixes?
Would you go with mono from a more reputable brand, or stereo from a Chinese brand, but at the same cost?
Stereo is a huge improvement IMHO, but it's far more important for everyone to have the ability to dial in "more me."
There are different ways to go about this. The first IEM based system I put together put everyone on a single stereo mix. It worked exactly as I expected, which is to say no one was really very happy with it. But it did exactly what it was designed to do, which is put a 5-piece rock band on this plane for less than $30K invested in new gear.
All of the other IEM systems I have had a hand in designing since gave everyone a stereo mix.
What stereo does is spread the audio sources out from left to right so you get more of a 3-dimensional sound stage. It's much easier to pick out instruments panned left to right than when everything is panned center. This makes it easier to distinguish between and pick out each sound source so you can run at a lower SPL and still hear all of the sound sources clearly.
The problem with everyone one sharing a stereo mix is most people prefer to hear themselvess about 6-10dB louder than all other mix elements. Also your instrument and voice should be panned either dead center or close to the center due to something called binaural summing. Binaural summing basically means that when you hear a sound equally in both ears, it is perceived as 6dB louder than if you only hear it in one hear. By putting the loudest sound source (you) near the center, you get the desired (perceived) +6-10dB at a lower SPL. Also IMHO it tends to be most natural to hear yourself in the middle.
So the ideal situation is for your channels to be panned near the center and for everyone else to be panned left and right in 3-5dB increments. I suggest panning no more than about L/R 15dB. You may pan slightly harder, but IMHO absolute max with most sound sources is about 20dB. The only type of sound source I would consider panning harder is stereo reverb. Keep in mind a good stereo reverb will distribute the energy across the sound stage, so you will hear it equally in both ears. In my experience 20dB LR is plenty for reverb, but it can vary somewhat depending upon the effect and your tone goals. I suggest experimenting.
So how do you get both stereo and 6-10dB of more me when you don't have enough channels. Although I have not implemented it, I do have an idea. I think it would work relatively well to build a composite stereo mix that everyone can agree on and share. Then everyone will need a small mixer like a Rolls PM351. The PM351 accepts a stereo/mono mix from front of house, and has a through for a vocal mic and also a stereo/mono through for an instrument. The PM351 has volume controls for the mix input, vocal mic, and instrument input. The mic and instrument channels also pass through the PM351 and go to front of house.
One problem with this idea is how to get the stereo mix to several PM351s. Two ideas: 1. Simply build a daisy chain that connects the PM351s in parallel. Most modern equipment uses impedance bridging instead of impedance matching. The impedance is considered bridged when the input impedance is at least 10X the output input of the device feeding it. The idea is the driving devices sees an impedance that is so high that it appears as open circuit. In other words the driven device does not load down the driving device. Because of this, a low impedance source can drive several devices if the input impedance of the driven device is high enough. Unfortunately the PM351 manual does not appear to list input impedance for the mix input...
so this may not work. I suggest contacting Rolls to find out the input impedance before going through the effort of building a breakout cable.
A better solution would be to use some sort of active splitter. Not 100% certain but I believe the Behringer MX881 can be set up for 2 in/8 out and runs about $100.
Because everyone has different tastes, it may still be somewhat difficult to share one stereo mix across the entire band. But if you have two stereo mixes it would probably work okay unless one person has really extreme demands. Obviously it will work better if everyone is willing to accept reasonable compromise.
Some additional ideas on IEM mixes:
IMHO low frequency instruments should generally be near the center of everyone's mix. For example bass and bass drum should be centered IMHO. There are two reasons I believe this: 1. one low frequencies are very hard to localize, so it will sound most natural if the extreme low frequencies are centered. IMHO panning low frequency instrument sounds extremely unnatural to me but YMMV especially with light panning. 2. Binaural summation is also an relevant factor. Setting low frequency instruments to the center means you can run them at lower levels which is less taxing on the IEM drivers.
If possible, I would also suggest you try to create an ambient space in the stereo IEM mix with an effect like reverb. Select a reverb that gives you a sensation similar to singing in the shower. Try a medium to short decay time with relatively strong early reflections. Creating a sense of ambiance can really help it feel more natural and also tends to improve vocal intonation.