Great idea! Sadly, your system is limited here. A newer model would work!
I was using a 2011 model doing this with an iPad as my remote for my TV & movie shows to my TV. It wouldn't be much of a stretch to link in your stereo instead of a TV. I was using: [https://itunes.apple.com/us/app/rowmote-pro-remote-control/id315316036?mt=8|Rowmote Pro] on my iPad (it could be an iPhone) accessing iTunes on my mini.
Today I'm using an AppleTV as the front end and controlling it directly from my TV.