Do speaker cables really matter?

As to the reference to adding a cable containing a passive filter. Clearly, adding a filter will affect the sound because it limits, attenuates, or shifts in phase the frequencies being transduced by the speaker. Referring to such as a "cable" is not accurate but so long as the manufacturer makes it clear that filtering is being added, I see no ethical issue.

This brings up what I believe to be two broad and different approaches, or goals, of home audio. (1) A goal of achieving the most accurate sound reproduction. I.e., the sound should be the same as the sound recorded on the medium, and ultimately, the same as the sound that existed at the time of the recording (this last nuance only comes into play when dediding on vinyl vs cd vs whatever other medium is or comes available). (2) A goal of achieving a sound that the individual finds most pleasing. Part and parcel to this approach is to treat the audio system as a musical instrument in and of itself. In my opinion, the popularity of tube equipment is driven by adherents to this approach.

I beleive that both approaches are valid. Just different.

Inserting a generic filter between the amplifier and the speaker drivers or crossovers is an example of the second approach. Choosing a generic filter- one not made for the specific speaker - is not consistent with the first approach. Inserting a filter between the amp and speaker (which in this case is equivalent to changing the properties of the speaker) could be a step in the direction of better accuracy, but in such case one would need to design the filter for that particular model speaker and to an extent, that particular model amplifier. At that point, it makes more sense to just design a completely custom set of speakers and place the filtering either in the speaker cabinet or in the amplifier.

I'd second Rockvirgo's comment; have you tried going back to the Kimbers for another listen, just to compare? Renewing the physical contact at the amp and speaker ends can make a noticeable impact on sound, often attributed wrongly to the new cable.
I'm not saying cables don't make a difference (I switched from heavy copper to silver speaker cables and noticed a very small change in frequency response), but they may not be responsible for the change you hear.

For years I was skeptical but they indeed make a lasting and audible difference; as someone said above, unfortunately.

I've found that, in comparison to Tara, Synergistic and van den Hul, Harmonic Technology ICs and speaker cables provide me with the timbre and frequency balance that suits my tastes from Joni to Zep to Miles to Beethoven and everything in between and around.

Yes, they matter. I think, the most important cables are the ones for the speakers and from Tonearm to preamp.

Thomas, you have a beautiful system, and I'm sure it sounds wonderful as well! Have you worked with aftermarket power cords? If not, you truly owe it to yourself. I have found that power cables seem to make nearly as much difference in my system as speaker cables. I hear very clear, significant changes to the system instantly when I use different power cords. If it were so subtle that it was negligible I would not recommend it.

If you are well aware of all this, excellent! I was not able to determine from your post whether you had worked with specialty power cords. I did a quick check of your system but did not see any listed. :)