Everyone's set up is going to be a little different.
I know that. Based on my limited understanding of what the OP was trying to accomplish, the Mac was (and is) out of place.
Thanks for the replies guys. To explain, I have had a home entertainment system for a number of years now nearly 10, it is a 'Control4'system and I have amps and speakers sytem in two rooms. My control4 is now getting old and is starting to play up. Because of this and the number of ipads, iphones , macs and atv3 we have, i was hoping that I could replace the control 4 'brain' with another type of 'brain' that would do all the control 4 wold have done. I could of course replace the control4 but this would cost over 2,000.Alos in ordert o get the control4 app it costs in the region of 600 EUR. I was hoping to get some type of computer such as rasberry pi or other machine which, when set up, could quite seamlessly manage the various inputs from cable tv, bluray media player and apple tv3 and output it through my Yamaha amp to my television and all of this to be controlled by a simple app pr maybe two, since all the hardware is in a different room. This would then really marry all the technology in the house.
I gotcha. Assuming your amps are indeed just "dumb" amps, then basically what you need is a "pre-amp".
I'm going to go back and make sure the terminology is clear here. A typical stereo or audio-visual receiver is actually a combination of a pre-amplifier and an amplifier. In component (rack) systems, these are separate pieces of hardware entirely. The pre-amp has the volume controls; hardware to receive and interpret remote control signals; hardware to process audio like Dolby Surround and DTS; and more. It is to this piece that you plug in the "source" units like a CD/DVD player, cable box, and so on. The pre-amp processes the video and audio signals, then routes them to the amplifier/TV set. If you have multiple amplifiers/zones, then it also has to be told which zone to send the signals to. The pre-amp is, indeed, the "brains" of the setup.
So... back to your problem. If your amps indeed are simple amplifiers, the you absolutely need a pre-amp. You don't have the inputs on a Mac (not likely any PC would) that are needed to plug your ATV, cable box, and so on into. You could probably buy a specialized audio/video capture that plugs into a Mac/PC to accept the inputs for its own needs, but then you'd have the problem of re-routing those signals and that's just well beyond what a PC is intended for.
Since you need the pre-amp to send to 2 different amplifiers (presumably one or the other as needed), then you need a pre-amp with multi-zone support. If you want to control this pre-amp with your iPad, then you'll need one that has wi-fi connectivity and explicitly supports the iPad, or work around it, as Adric has already elaborated on quite adequately. If you don't need to control this from another room, then quite frankly using a "task-based" universal remote control is a whole lot easier (and cheaper) if you set it up correctly. I'll see if I can find a couple good examples of pre-amps and post them back. (EDIT: Or not. I can't find any that aren't insanely expensive.)
P.S.: Say Adric, I like your taste. I have a Harman Kardon AVR myself.