Output impedance CD/DVD Players

I'm trying to better understand the spec called "output impedance" on CD and DVD players. I've read the definitions and have talked about it with others but I still don't grasp it fully. Why is it desirable for a CD/DVD player to have a low output impedance? Does it mean that the lower the output impedance, the louder it will play (in dB's)at the same volume setting on the amp than another CDP will produce with a higher output impedance? Does that make sense? Please explain. Thanks.
Not necessarily, assuming both players produce the same output voltage and cables are of reasonable length.

Output impedance for any component can be modeled by an internal resistor in series with the output. The reason it is listed as part of the specs is so that you can choose a "load" (another component) with an appropriate input impedance.

For line level signals, the rule of thumb seems to be that the input impedance of the load be at least 10X the output impedance of the source.

Here's a good example: http://stereophile.com/cdplayers/1005cary/index5.html