How old is the CD player? I think you can tell by the first four numbers in the serial number (0207/335 would mean July of 2002) The little tubes in the A.A. are supposed to be good for at least 10,000 hours (14 months of being on standby or in use) and that's probably a conservative estimate. The tubes would probably go bad one at at time, but I suppose both tubes could be well past their "freshness date" if the player is a couple of years old.
The player is usually very quiet.
The player is usually very quiet.