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

I am about 240 hours into the Clear Day Double Shotguns after removing older Audioquest all copper Earth series cables from my system.  The "heaviness" of the AQ cables' contribution to the overall sound was obfuscating the transparency that the rest of the system was capable of delivering but not with THAT much copper as I had two pair of the Earth biwiring my Vandersteen Treo CTs.  

As usual John Rutan from whom I purchased the Treos warned me that I had too much cable for the speakers and as usual he was dead on.  Hearing into the soundstage now is so satisfying.  Hearing subtle details that were masked by the overly "bassy" sound before the Clear Days makes listening to even very familiar tunes an experience of rediscovery. To be clear, the Clear Days are reproducing bass just fine...the key is they're not overproducing it to the detriment of the music.

And yes, as virtually every Clear Day poster has mentioned, Paul Laudati is a true gentleman and will want to counsel you about how his cables might fit best with your system.  Listen to him.  From my experience, he does really know his product and how it is likely to interface with your components and speakers.

@edward506 (why does the @ only sometimes work?) - I totally get where you’re coming from. I was sceptical as well, read all the articles saying all that matters is resistance, maybe capacitance.. I bought blue jeans cables and didn’t even bother with power cables. Curiosity eventually got me to at least want to try messing around with cables. No way I was paying crazy cable prices though, so I chose to make my own cables.
My cables now are all DIY. I eventually realized that it was worth spending a little bit of money on the conductors and connectors and exploring different architectures.

Saying cables make a difference doesn’t mean I am advocating dumping tons of cash into a decent set.. there are other options.

Not sure on the "@".  I'm new to posting on the forums though I've been collecting listening to and ogling audio gear for over twenty years.  I appreciate that. Fair enough.  I'll do some more listening to various cables.  I still, so far, find the speakers and room acoustics to be the most critical.  But you only know what you know and can be surprised by what you don't.  

Edward- you are completely correct. Having components that play well together, well made speakers that the components can handle and acoustic treatment of the listening room all impact the sound of a system more than exotic cables will, as long as the basic cables are of sufficient gauge and quality. But once all the pieces are in place, cables can help bring out even better sound.