What speaker cable made a major difference in the sound quality of your speakers??

The Vertere Pulse D-Fi interconnect and Snaics together with the Pulse X mini loudspeaker cables, into a all-Naim system.
Warmth, detail, coherence, richness, natural voices and not trace of dullness or artificiality. The whole set (the 'SNAICs' are the two special ICs connecting power and signal to and from the PSU, the preamp and the power amp) cost me something like £1550 (loudspeaker cables were 2 x 6 mt).
Nothing I've heard or owned has had a 'jaw dropping' effect to me, but they have my total respect. Made in London, UK.

When I went from Omega Micro Planar 1s copper ribbons which were a significant improvement over the many different cables I've had in the past to Omega Micro Planar 2 copper ribbons. What's the difference? In a nutshell greater resolution, leading to more accurate tone, better separation of voice and instruments, more realistic sounstaging and imaging and greater overall resolution of detail. This cable is decidedly not a "tone control" as some cables clearly seem to be to me. It is a conduit to allow more of the music through. I have found Nordost cables to have similar qualities as well.

Pretty much any 12 gauge speaker wire bought at Home Depot, Lowes or Radio Shack.  If you have the money to buy ludicrously expensive cables, put that money where it counts most and buy better speakers for your ears and tastes or be a slave to cognitive dissonance.

Thank you for saving us from this Tom foolery Edward. We've obviously been fooling ourselves for years and just needed you to set us straight. Praise jah!

Totally agree Todd.  It's just how human beings work.  Not limited to audio cables. It's true of all of us but especially when we consider ourselves "philes" of any kind. But hey, if you enjoy getting into the mystical nuances of subjectively undectable sonic details and it's worth it to you to do so, then have a blast, I don't really care.  But maybe someone reading this forum does.  After all, this is a place to buy things we otherwise couldn't afford new and so I assume getting ripped off is more painful for those buying here than those with the money to buy new at appointment only audio shops. Your mileage may vary.  Try doing some well controlled double blinds though if your confident.  Just a thought.