What is the affect of cd player?

Your source component is the most important piece. It is impossible to improve the sound down stream no matter how good your speakers or amplification are.

Well, garbage in equals garbage out of course, but I believe speakers are the most important part of the system.

Based on the reviews I have read, you would have to spend over $5,000 to better the Cambridge 840C. I have never heard a player that cost over five grand so cannot confirm or deny.

The degree of difference between good digital, like your Cambridge, and top shelf digital is relatively small. And probably not a worthwhile upgrade at all unless the rest of your system is highly resolving and up to par with it.

It's all about that last 1% though, so the value proposition is up to you. There's also the matter of "flavor" once you get into those regions, where most of the contenders are rather amazing, but each has its own character.

I guess what I'm saying is "is there any other part of your system that could use an upgrade first to make a digital upgrade worthwhile"?

Enjoy,
Bob

PS - then again, there's more fun to be had in vinyl (any more expense), if you haven't tried that route yet.

There is no "most important" in an audio chain. Think of yourself as looking at a garden(your recording of musicians in the original venue), through a number of glass panes(source to ears/your electronics and room). Does it matter which panes of glass are dirty or off color, with regards to what you see? Some components have a harder job to perform than others. I've always considered converting a series of electrical impulses into sound waves/music(accurately/believably)and interfacing that with the average listening room, as the most difficult to accomplish. But, that's just my opinion. The player you own is highly regarded/sounds damn good, and yes- You'd have jump a couple performance levels to improve on it(at least get into a tubed output player). Again- my opinion/experience. The improvements in the upper tiers of what's available in players are way more than subtle, affecting sound staging(width and depth), image size and height, instrumental timbre, detail without grain/stridency, frequency extension in both directions.... well- basically everything important to musical realism. As stated- Whether it would be worth it to you to upgrade, would depend on the rest of your system, and your ears.