Unconnected, there will be no current at all. While signal transmission is often mainly a voltage modulation process, it is likely some current flow may be important to breaking in. A short could be dangerous to the equipment. I suggest connecting the player to the preamp, turning the preamp's selector switch to select the player (or else you might end up with an open circuit and no current again), and keeping your basic amp connected but off, unless you want to listen to the CD.
