I plugged an MP3 (Rio specifically) into the audio in port. The sound is good, clear and loud; but what happens is it stops playing and puts itself into power save mode. Any suggestions would be greatly appreciated.
Your MP3 player must either be faulty, or misconfigured. If it goes into powersave mode, it’s nothing to do with the aircraft audio system. I’m not personally familiar with the Rio devices, but I believe they have a configurable power-save timeout setting. You may just have this set to something other than Never.
A lot of Cirrus owners (me included) have had excellent results using the Archos Jukebox or Recorder - they will also run off the 9V supply that is provided for the headset power (at least in older SR2xes).
In reply to:
A lot of Cirrus owners (me included) have had excellent results using the Archos Jukebox or Recorder - they will also run off the 9V supply that is provided for the headset power (at least in older SR2xes).
May I also suggest the Apple iPod, arguably the best MP3 player on the market, and available for Windows or Mac. You can get a cigarette lighter adapter to power it in the Cirrus glovebox, but, since battery life is 10 hours, why bother? The FireWire interface provides blazing download speed, too.
The iPod is indeed a nice piece of gear and I wouldn’t disagree that it is probably the best unit currently available, but the Archos Recorder 20 downloads just as fast (USB2.0), has more features (specifically recording) and is less than half the price of the iPod.
But then Apple users have never been swayed by price 
I will echo the iPod. It is fantastic to have for its variety on a long trip. I agree that your Rio must be configured to go into powersave mode after a period of time. Plug it into the cigarette lighter and see if that overrides the powersave mode since there is external power.
Clyde,
In reply to:
But then Apple users have never been swayed by price
Ah, but we have! The Gaertner group and other industry think tanks have repeatedly shown over many years that the life-cycle costs of Apple equipment is lower than that for windoze machines. Most of the difference was in the vastly different amount of support required and in the longevity of the Macs.