So, wait... You want to connect the PS2, via optical, to a CD player, which is connected (via what?) to speakers?
I assume by CD player you mean some sort of A/V tower.
At best, yes it will pass the signal, but only in stereo (or even mono).
From what you're saying, it won't pass along any PL or DD/DTS digital tracks, though.
I don't see why you'd want to, if the "CD player" isn't a reciever with a decoder. Whatever quality gain there is, if any, surely isn't worth it. You'd be just as good getting the audios from the PS2's outputs to to "CD player"'s ins.