Most important component??

The source,always has been always will be.Doesn't matter what you do downstream it begins at the beginning.

The most important component for a CD based system would be a turntable.

Besides Room, i would say:

1. Recording
2. Agree with duke: Loudspeakers-Amp Matching
3. Preamp
4. Source
5. Cables

markwatkiss, i agree the source is all important, but if (if) most players are technically excellent and differ little, the choice of which to choose is of less priority in seeking good sound, whereas speakers and the rooms they are used are highly variable - so sure, the Cd player has to be good (the recording even more so), but I think you wont find a lot of difference between them in their effect on performance.

My opinion about the components is simple.
System is like a window to a beautiful outdoor scenary.
My window is constructed with 4 layers of glass.
All layers better be transparent or image will get blurry.


Countdown:
5)Accessories, tweaks, cables, voodoo BS.
4)$$$Limits
3)Speakers that match your taste, budget,
room and rest of your equipment
2)Your listening space, acoustics, component sinergy, proper system setup and calibration
1)You.

Surprised????
I hope not. Without your knowlage, experience and most important passion for music all of the above would mean very,very little.

You need roots to get the fruits.