How important are speaker cables to the sound emanating from the speakers?

Freediver, I will politely disagree with your conclusion regarding the nature of components and benefit of cables. I have built many systems in the $2-5K range, and every one has been as sensitive to cable changes as the "big boy" rigs. No, you cannot expect precisely the same result as with better systems, but the cables do effect significantly - by that I mean easily heard and repeatable changes - even modest systems. 

Two incidents to consider. The first system I tried to test cabling on was what would be a solid MidFi rig. It was nowhere in sight performance wise to what I can build now. My first cable test was some extremely thick cables purchased from a home improvement store, with such gauge that when I twisted all the individual conductors together I could barely fit them into the posts of the amp! Instantly I heard the difference between it and lamp cord, and I knew at that moment the wires are critical. That was a revelation which occurred on a system with compromised performance and with very average cable, but with large AWG.

My second "I don't believe it," moment occurred a few years ago when I had a boom box which took a C7 plug. I had just upgraded my power cord for Sonos to an aftermarket one, an Audioquest. I wondered if the difference in a power cord to a boom box could be heard. I knew enough not to discount the possibility altogether. Yup, it did make the boom box sound different, another evidence that cables matter no matter what the electronics.  :) 

I don't look to professional studio personnel and technicians to know how to set up a fine home audio system. I advise not to listen to them. 
Even the venerated Alan Parsons showed his gross ignorance in this respect, as I commented on years ago. 

Bill Dudleston  at my request  upgraded my Legacy Whisper DSW speakers to "Clarity Edition" as an experiment regarding efficacy of internal speaker wiring. You can read about that also at Dagogo.com. In brief, he also suggested a caps change to Clarity Caps (no relation to Clarity Cables). He wasn't expecting much, but was impressed by a measured 2dB improvement in the bass. Some would suggest neither the caps nor the cables should have made a change. It did, measurably.  :) 

studioray, I ask that you not take my directive personally. I have for some time now eschewed the advice of those who prompt the acceptance of blind testing and the conclusion of cables being of insignificant/marginal importance to the sound quality in comparison to components and speakers themselves. I find this to be common in pro sound. 

Perhaps I read your intent wrong, but there are a fair number of people who enter discussions on efficacy of cables and direct attention to blind testing promoting a conclusion which precludes cables as an efficacious means of improving home systems. Most of us here are familiar with blind testing, so you didn't really add much to the discussion. Perhaps if you were to discuss your experiences and conclusions rather than try to stir things up to foment argument I would have reacted differently. 

I have had many contacts within the audiophile industry with persons on the pro side, and read a fair bit on ABX. I also had the pleasure of conducting some blind testing for myself when I reviewed the ABX Comparator from Audio by Van Alstine. That settled the matter for me; I was able to consistently identify cables in blind testing. In fact, cables were easier to identify than amps! So, since that time I have little patience for the entire "blind testing shows there's no difference in sound," thing. 

So, my conclusions and advice has little to do with you, per se. You simply gave me the opportunity state my perspective. I should add that I do not turn away from listening to those on the pro side entirely. I have had many wonderful discussions with people in the industry who work both the home and pro side of audio. They are a wealth of information, and as you say some of them have been marvelous to interact with. So, my first statement was too strong; I should have limited it to cables. 

However, I also see an influence from the pro side that prompts audiophiles to think that quite inexpensive amps, DACs, etc. are as good or better for building home audio systems. I have not spent as much time on that issue, so I won't comment now. Perhaps as time permits I will do as I have on other topics such as "Burn In" and conduct comparisons to reach more firm conclusions.  

Anyway, there's enough room under the audio tent for divergent opinions. Of course there may be some producers and engineers who excel in home audio, but I aver that if they have dismissed cabling as a critical element of a system they do injustice to the task.  If their conclusion is that any cable will do, imo they should be avoided. There are all manner of discussions and admonitions here about reviewers, dealers, manufacturers and individuals. Pro audio is not exempt. 

Now, one last note; I have no interest whatsoever to debate the merits of blind testing or cables. I have shared my experiences and people can read it for themselves. They can also read my many articles at Dagogo.com on reviewed cables, which include technical discussion from the designers, some of whom are engineers. I allow the cable manufacturers to explain why they made their design choices. Obviously, every cable company� thinks they have the solution, but collectively there is a wealth of information on what influences cables' sound, and how it relates to setting up home systems.