I find it very interesting that there is so much controversy on this subject. On one side you have the 'purist audiophiles' who think that you're crazy if your cables aren't suspended on a polymer web hand woven by french gypsies who are electromagnetically inert. On the other side you have the folks who think that any attempt to improve the quality of your sound by upgrading the quality of cables or power is a silly, useless waste of time.
There's tremendous rigidity of thought on both sides. Question I have is: who actually wants to be a rigid thinker? When you're young, we call that a know it all. Is it any better when we're older?
The FACT is that cable makes a difference. It's actually makes little sense to argue otherwise. Let's look at HDMI cable as an example - I have used very cheap HDMI cable and I have also used expensive cable. To me, the visual differences are not very noticeable - there might be a difference but if there is one it's not something that I'm too concerned about. I'm told I'll get deeper blacks, slightly more sharpness, etc, with better cable. Doesn't matter to me. See, I don't care with regards to HDMI - but it doesn't mean that better cable won't improve the quality, it just means that my feelings on the subject aren't too strong. Now, take the cheap HDMI cable, and stretch to, say 15 feet. Suddenly there are HDMI handshake issues. Stretch it out to 50 feet, and there's no chance my DVD player synchs to my TV. Replace it with expensive HDMI cable (as I have had to do), and everything is fine. Hmmm - better cable handshakes, cheaper stuff doesn't. Why? Maybe the better cable has slightly less transmission loss of the digital signal.
Now, look at audio. The interconnects as an example carry similar signal, though because it's analog there's no binary connection like with HDMI. The signal can change in infinite ways between the preamp and the amp, and the amp will still take that signal and pump it way up. These changes are really small, but the signal itself gets amplified many many times, so whatever change there is becomes much more obvious. The more accurate the amp and speaker - and the better the room sounds - the more obvious these changes become. Yes, just like an HDMI cable can change the signal enough to lose synch, an analog cable can change the audio signal enough to modify the sound. In fact, it makes much less sense to believe otherwise - to believe that somehow the microdynamics of the signal woud be unchanged by the cable. That's actually far less reasonable a position to take. The material of the cable, the length of the cable, the diameter of the cable, the dialectric, the quality of the ends of the cable: how can these NOT affect the sound? Well, of course they do.
Take it to an extreme: use a hair-thin, unshielded strip of copper to connect all of your components. Does that sound good? Have fun with that. One of you guys uses 14 gauge cable. Why not 50 gauge? Probably because you know that the thicker the gauge the better the transmission. So why stop at 14? You all probably believe that the shielding matters. So why not the kind of shielding? Well, actually, it does matter what type of shielding.
How about inductance? Yes, that matters too, just look at low-inductance cable - like Goertz. Ever try it? The cable's material and winding pattern allows the electrons to run very smoothly down the signal path - the US military uses that cable for a number of installations where speedy transmission is essential. (oh, yes, the military believes VERY strongly in the differences between cable). The downside? Low inductance usually translates into high capacitance. Go ask any electrical engineer what high capacitance does to audio (you may know the effect as what we call a low-pass filter). Not surprisingly, Goertz is known in the audiophile world as a good cable to smooth out harsh sounding systems. B&W dealers used to sell it with their older 800 series speakers to offset some of the tweeter's bright qualities. Now, according to some of you this is all nonsense, no cable can make the sound any different from another. But in the case of Goertz, the low-pass effects of the cable reduces some of the higher frequencies. Oh, and BTW this is all fully measured - the response of the cable (both its electrical properties and its effect on sound) have been fully measured. Go ask the Navy.
So here we have cable material, winding pattern, inductance, resistance, capacitance, shielding, gauge, dialectric, length... each of which clearly have an impact on sound (that's why you are not using a single strand of unshielded copper for your systems). Each of these is fully measureable. So I ask: how is it possible that anyone can claim that cable doesn't make a difference in the quality of a sound system? Not to be snarky, but it's like believing the earth is flat even after seeing pictures proving otherwise.
I read the articles that Ethan put up - I appreciate his biased passion for his belief, but from my perspective (and yes, my perspective is biased, too), his is a singular mission: to show that any claims regarding high-end audio - outside of the use of his own acoustic panels - are BS, a pseudo-science, and that somehow all of the incremental changes that I and everyone else has heard in my system were a function of slight adjustments to my ear placement. Instead of the more likely probability that the changes to my system were the outcome of significantly different materials and cable design carrying the signal to my amps.
So here's the thing - if you're happy with your sound and don't think that cable makes much of a difference, that's great. Being happy with your sound is the only thing that matters. If you're not happy, you should try playing around with different combinations of componentry and cabling. It really makes a difference. But commenting so rigidly on someone else's journey to audio nirvana is just not cool, and it's not the reason why most people use these boards.