Yeah, now that you mention it, the biggest impact on whether the music coming out of your system sounds good or not, is the quality of the playing/singing of the artist(s).
Good music, poorly reproduced is still more enjoyable than bad music, excellently reproduced. (But of course, good music, excellently reproduced, is the goal.)
Continuing in a smart-aleck vein, I think that the most critical component is the clamp that is used to solidly hold the record down to the turntable. Or, for the digitally-minded, it is the transport used to rotate the CD/DVD at precise speed.