Not all cds players sound different -- just because it is expensive means very little. At the same time do not expect to hear differences in high resolution sources when you run them through receivers analog or digital -- I have a Marantz 4300 which is newish and it could not distinguish crap from a filet mignon because it basically presents a sludge result. I also tested the absolute top of the line Yamaha receiver before I left and it soundedpretty much the same as the Marantz -- caca.

This is not to defend pricey cd players or pricey amps. I have heard the $30.00 Class T Sonic Impact sound considerably more musically satisfying than an over $1K Highly raved about Musical Fidelity. I have also heard 5 disc Sony players at $199.00 that were just as good and in one case better than highly raved about $1k+ cd players (I listened in a line level matched blind test and successfully determined the difference). Differences are less important - better is important.

Speakers make the largest difference along with the room positioning of speakers and your listening position. Biggest difference and most important differences however are not necessarily the same thing. I may like wildly different loudspeakers each has a voice which I may like -- but the rest of the gear may make a system produce magic or produce annoying dreck. Which it is will be different for each user.