rtweed:
Well you asked me to quote references and provided the moderator doesn't remove hyperlinks as he has done before, here are some. I'll add enough description that you'll hopefully be able to Google for the articles anyway. The best source in my opinion for such evidence is the newsgroup named rec.audio.high-end which is also available as a Google Group. The threads I'll quote will contain numerous other references to support the claims that are made.
A great all-round summary in the thread titled "Best 3 ways to significantly improve a stereo system":
http://groups.google.co.uk/group/rec.audio.high-end/browse_thread/thread/385b5581913187ad#
While we're at it, on the subject of the sound of cables, see the lengthy discussion in the thread titled "You Tell 'Em, Arnie!":
http://groups.google.co.uk/group/rec.audio.high-end/browse_thread/thread/8dc7089fc397bdad#
On amps (and more on cables), again same group, thread titled "The Carver Challenge":
http://groups.google.co.uk/group/rec.audio.high-end/browse_thread/thread/9193e3692a71c833#
On bi-wiring and speaker cables, thread titled "Bi-wiring?":
http://groups.google.co.uk/group/rec.audio.high-end/browse_thread/thread/e2dd69024fc41c13#
In fact anyone who seriously considers himself or herself an audiophile should spend time persusing the numerous postings in this group.
I haven't read the cables related posts listed principally as I've a fairly ambivalent view on these things; the cables I'm using right now were £30 and £60 apiece and do the job well enough for my ears. I dropped down from Nordost Blue Heavens to Audioquest Copperheads and that gave me an improvement. I noticed one anyway, so whether or not anyone else does is pretty irrelevant to me!
As for the speaker thread in the newsgroup, apart from a pile of posts on the many virtues of finding well recorded CDs in the first place (including well mastered ones), I see an awful lot of opinions and not a whole lot of fact. Which is as it should be of course. That those opinions appear on a "high end" newsgroup means nothing to be fair in as much as those which are expressed are no different to the ones I've heard and read about for the last decade and more here there and everywhere.
Peronsally, I would go along with the ones which suggested good masterings on your favourite recordings and getting a decent record deck. The ones who said "buy some good speakers" missed the same boat that you did. They think that this is the only way to make a big difference to the sound of your music, maybe because that's where the sound comes out of...I dunno.
And you seem to have contradicted your own argument; in the thread elsewhere on here where the OP asked for recommendations about replacing his Marantz CD52 Mk2 with a CD6003, you suggested getting a DAC, but, by your own logic (as the OP wasn't having issues with the player's ability to still spin discs), shouldn't you have suggested buying new speakers?!