$500 mini system suggestions, Bose need not apply

Hello all. A friend of mine is a Speech Pathologist. She works with children and adults with mental and physical disabilities. Recently, she attended a conference on Music Therapy. The main speaker adamantly suggested using the Bose Wave radio/CD and "nothing" else. Upon hearing this, I immediately talked her out of it; reasons why need not be expanded upon here at the 'gon. Anyhow, I'm not too familiar with the currently available mini systems, but recall that Denon, JVC, etc, have produced good ones in the past. The key here is clean sound. A lot of her patients are autistic. She warned me that distorted sound can sometimes upset these special patients. Her main request is for clean, full sonics. I was thinking a decent frequency response would be nice as well (40hz or 50hz - 20khz), perhaps a sat/sub type system, source only needing to be CD playback. Her office therapy room is about 15' x 7'. Since she was originally willing to spend $500 on the Wave, please try to keep suggestions in/under that price range. Also, she needs receipts and a warranty for business purposes, so please suggest equipment she can purchase new. Any thoughts or suggestions would be greatly appreciated. Thanks for your support.