First, there are "different" connectors - the old "Dock" connector and "lightning" port.
I believe iPhone 4s is old Dock port.
You did not mention your iPad model.
MacBook Air - it does have a "audio out" port.
If you have all the different kind of port, the best bet is using "Apple TV" to play your contents through wirelessly, only iPad 2 (and newer), iPhone 4s (and newer) and MacBook Air (mid 2011 and newer).
My question is - what kind of sound system do you use.
USB input? or typical "Right/Left" analog sound input?
Digital sound input - SPDIF (Coax or optical)
All these would the deciding factors for some certain peripherals - like "dock to audio out", "USB to digital out"
with your "receiver" capability.
ok, that did clear up the devices you are planning to use.
You probably will need a 3.5 mm (stereo) to Mic Jack - Male to male for your mixing board -- since all the devices have the earphone jacks.
Here is one of the examples - you can take a look.
Unfortunately, it will be Mono when it reaches the mixing board.
If you have more than 3 RCA jack inputs on the mixing board, then, you can use 3.5mm to RCA jack - it will be stereo. for example -