ok here are the only specs THAT MATTER ON A CD PLAYER

signal to noise ratio- get one that is 100 or higher more like 105

and the voltage on the rca outputs. get 4v or more.

kenwood makes a few 6v and 4.5volt but try to stay 4v or higher.

the rest of the shit matters but not as much as these things.

if you have a shitty signal to noise ratio you might notice that fuckin annoying engine wine