I have owned one of those recievers and it has DLNA and AirPlay.
so if you have a pc that has itunes on it, you can stream over the network to your amp. The mediamonkey is one app that you can use. I don't know if they make you pay for it or not. I ended up using Foobar2000 it's free and has a whole bunch of plugins that you can get for it.
The one that I paid for was MonkeyMoteHD for my ipad that interfaces with FooBar2000 and gives me the ability to view/search/queue up all my music, make play lists etc.
Now I went with a different approach to you in I wanted quality in the sound that I was getting and found that when steaming the songs were getting re-encoded to a lessor format, such as MP3 to be streamed. So I went out and bought myself a small Zotac Zbox HTPC (small PC) and loaded up a copy of windows7 that i had laying around. Loaded my FooBar2000 onto that and hooked it up via a toslink S/PDIF cable. I have all my music sitting on a Synology NAS drive so that might have some bearing on what worked for me and how I did it.
Start off with something free and see if it works for you and what you find to be missing then go from there.
If you have a small pc or laptop with HDMI output on it, then you can get Daphile http://www.daphile.com/#download
that runs like a squeezebox and it's free and works pretty well.