its Linux. Get the rack mount version of the small green computer.

Another suggestion for the Spotify issue.  You could use something as small as the Onkyo TXNR509 for spotify.  It's obviously a second AVR, maybe having 2 complete AVR's would make things even easier on you.  Just a thought.  

As mentioned. It's a Linux based media server. It runs the squeezebox server and can provide multiple streams of audio from either multiple USB audio cards or out of 5/1 and 7/1 cards. Squeezebox is a Logitech creation that is capable of virtually every streaming media service. RTI has a driver for it and it sounds very capable.

You can either do a Squeezebox device like the Touch along with a computer that has the server software running or you can do a Vortex box which is the Linux based server mentioned. You can take an PC (even an old POS) and load the ISO file that changes the computer to Linux. Once you do it you can't go back so just know that before you start. My guess is that it will take a couple of days to get your head around it but once you do it's more than capable. This is coming from someone who only just purchased two Squeezebox Touches and who hasn't had time to test and come up with a GUI.

How are any of these complete solutions cheaper or better than him just getting another iPad? If he doesn't want it to leave the rooom then mount it on the wall. 

Nothing is cheaper than free. Find an outdated computer and convert it to a Vortex box. In theory of course because I haven't done it yet. LOL

Vortex doesn't support spotify. And even if the OP has two way RTI equipment he would still need to integrate the vortexbox into the system which will take some work and $$ and the interface won't be as nice as the iPad interface. I would either go Sonos or just get another iPad. 

You are right. Not sure if and when it will be supported by RTI either. I just don't think that another iPad is the right move. I would agree it functionally work but it would be an odd step for the customer. Plus you are relying on the wifi connection of the iPad which doesn't always work great. I also don't like the idea of putting a Onkyo receiver as a source. And functionally it will work but it seems a little hokey but would be better from a seamless control standpoint. Sonos is always a good option and probably the best for your application. IMO

so sonos it sounds like is the only choice. Does ANYONE have anything that allows basic control of sonos via ip? i could have swore someone on here was getting basic control through crestron/rti/elan

If thats not possible, is a media center PC with IR control an option? i build PC's i just never a media center, any good IR cards/software? it would be strictly for music. he called me again asking if ive come up with something, i did ask him if he was ok with using a separate controller and he kind of him hauled around it. He loves his RTI and doesnt want to introduce something else (i cant blame the guy)

I wish denon would get their ass in gear, this whole problem wouldnt be a problem if it was built in already. I mean jeese, onkyo has it already. :)

You can't get around using a seperate device for control unless you use an onkyo reciever. There isn't anything simple for RTI and spotify. There is a basic sonos driver but it won't let you select anything. very basic controls.