I recently had to update the plug-in I was using because it was no longer supported by WordPress, which can be an issue. After trying numerous players, I didn't find what I wanted (a simple player with no bells and whistles). I opted to use the HTML5 player code found here: http://www.w3schools.com/html/html5_audio.asp. Here it is in practice: http://www.anthonyhansen.net/voice-over-demos.
Thanks so much! I will check it out. I agree: oddly difficult to find a simple/good one.