If your going to do the decoding in your pre-pro, a high end player is only going to give you a better transport and you'll probably never notice the difference. You'd get much greater effect dy doing the conversions in the player and feeding an analog signal to your pre-pro.
If your into SACDs, the sound that you get with a 2 channel SACD should give you some notion of what you could expect with a high end CD player.