I searched a bunch of old discussions and could not find anything on this. I am currently considering switching to in ears. Here is my question. We play a bunch of different clubs with different sound guys. Is there anything I can plug into there board so I can control my own monitor mix with an iPad on stage?
Take for example the Mackie DL 1608 or say something like the Behringer Powerplay. I believe it would require all instruments and mics to go through it. But is this something where instead of that I could connect it to the sound guys board then control on stage my in ear mix?
Hopefully some of this makes sense.
Makes perfect sense, you done good...

I used to do this for a living for 19 years, so I hope I don't make it sound too easy...
To accomplish monitor mixing as you describe, the console (board) has to be digital. That's the only way that remote mixing via iPad/Android tablet or individual mix station can be done.
If you are lucky enough to play in a venue where a digital console is used, the easiest way to accomplish this is to attach a good gigabit router (a Netgear R6300 at approx. $175, just as an example, there's several good ones) and have the musicians download the appropriate app (supplied by the console maker) to their smart device (iPhone, iPad, Android device). They can then log into the router and control their own mix.
I call this easy because it doesn't involve separate mixing stations that need a Cat5 cable run to them or the appropriate interface card attached to the mixer. The only external device in the router and your smart devices. However...(you knew this was coming....)
You have to have a willing and knowledgable house sound guy that knows how to set up the router. I say willing because it can be tricky to set up the router and then, he'll inevitably have to help you or someone get the app set up and connected to the router. That may not be feasible for various reasons.
Using the mix stations works well, but again, you have to have the interface card for the mixer and the stations. That all gets complicated pretty quickly for a one-off gig and working on the house console. Not to mention you'd have to carry many systems for all the consoles that are out there. This really isn't feasible at all, until you start carrying your own mixer. Which leads me to the optimum situation...
There's a lot or rack-mount solutions out there for digital consoles. I'll list the Behringer X18... [Invalid or Expired Link Removed]
And the Behringer X18... [Invalid or Expired Link Removed]
The QSC Touchmix is a good unit...
Link Removed You can connect a router to theses units, or use the built-in router, in the Behringers' case and have everyone control their own mix with their smart device.
And there are other good units out there that I personally haven't used.
You can get one of these mixers and a small split snake such as this...
PSX | Hardwired Passive Split snakes with Short Trunks You plug your band inputs into the snake, then one set of XLRs to your mixer and the other set to the house sound's audio snake.
This set-up will allow you to fully control your own monitor mixes and be totally independent from the house sound. Yeah, yer gonna spend some money (what, $1500, $2000?), but it puts you where you need to be.
My personal set-up is a Behringer X32 console, a split, and my own mics, mic cables, mic stands, and a couple of subsnakes. I wanted to be 100% self-sufficient on the stage, especially after a couple of bad monitor experiences, one of them with the sound company I used to work for!
MODS: I would love to see a sticky in the live sound section where we could all list our set-ups for us to point to and others to see and get an idea of how it's done and approximate cost.
I hope other folks such as s09 (Steve)will list their set-ups to give you some ideas, although I know they've done that several times, that's why I bring up the sticky idea. However, everyone here is willing to help however they can, so I"m sure you'll see some set-ups listed.
I realize that this may not be quite the answer you were hoping for, but it's not that bad to get into with your own system.
Good luck!