order of improving sound quality in system?

Thanks for all the input everyone :)

I agree with Hack, though would add power (specifically dedicated lines) as being only slightly behind cables/wires. I came to this conclusion kicking and screaming, initially placing a much higher priority on speakers than on source (dead wrong, but some of us are slow learners). Any speaker manufacturer - Wilson springs quickly to mind - who tries to tell people otherwise is working a scam, as far as I am concerned.

Of course if your system is wildly unbalanced by one poor component, including speakers, it is not going to sound good. Balance and rationality is still of great importance in deciding on upgrades.

Speaker ----> Cd player ----> Pre-amp/Power Amp

That's for me. Cable should come last.

Regards

I think there is no "right" answer to your question. Speaker selection is Very important, but so is the preamp, poweramp, and particularly the source. Ultimately, it is the synergy between components and cables in the system, and the weakest link that will give it away. If your system had good but revealing speakers like, for example, B&W N-805, it would not sound good with a poor digital source, and you would be much better of with speakers offering less details and resolution. On the other hand, an excellent source, is more likely to provide a more positive overall effect in your system regardless of other system components. So in regard to your question, you really need to be more specific as to what the current components are...
Good luck.

I hate answers like this, but, it depends! I've been doing some upgrading over the last year. I started the upgrade process with some pretty good speakers (magneplanar 1.6 QR) that I was ready to sell because my system sounded pretty awful. Thinking through a few questions before I started helped me significantly improve my system without overspending.
Q1. What don't I like about the current sound?
Answer: Digital glare, grain, weak bass, room resonances, poor soundstage.
Q2. What is causing what I don't like?
Answer: Digital glare--CD Player, grain-- cables and amp, weak base--amp, room resonances-- corners that needed treatment, poor stoundstage-- CDP, room, and speaker placement.
Q3. I've got a lot to upgrade, what's the biggest bang for the buck?
Answer in order of impact:
#1 Room treatment for $100 made a huge difference
#2 new DAC
#3 amp
#4 cables
The learning points for me were
1. Good speakers + bad supporting equipment & room = bad sound
2. Be patient. Try to identify weak links in the system. Upgrade one thing at a time, understand if the change fixed the perceived problem before making the next sysmtem change.
3. Look for well reviewed/high resale value equipment. This allows you to experiment and resell if your equipment if the change doesn't address the problems.
4. Have fun and enjoy the music!