OK, I have done a lot of research on speaker wire, and read many explanations from people much more qualified/intelligent than myself (I.E., scientists) who basically say that "copper wire is copper wire", and that a 12 gauge Joe Blow brand is not going to sound any worse than the highly over-priced placebo-effect wire sold by the big mega cable company with the deceptive marketing.
That being said, I recently upgraded my receiver, and at the same time because I had been using mismatched speaker wire (2 different products by the big M, one for my mains and another for my center) I decided to invest in new speaker wire. I purchased a 100' spool of 12 gauge speaker wire by a company called Pyramid Audio, as it was highly rated (value/money) on the site where I purchased it.
After hooking up the speakers to the receiver I was replacing (hadn't set up the new receiver yet) and using identical lengths of the new cable for all speakers, my wife and I IMMEDIATELY noticed a difference in sound. This is no placebo effect. The sound now sounds "fuller" in a way, but not necessarily better. In some ways it sounds muddy in the mid-range, and overall it just seems more harsh sounding when I drive my speakers hard.
I replaced a "THX certified" speaker wire (the company's 'standard' wire which is double strand insulated 16 gauge wire) with Pyramid Audio's made-in-China 12 gauge wire. As I said, the sound seems fuller, but somewhat muddier. Also, I'm noticing a distinct buzzing sound through my speakers' tweeters. I have the speaker wire run on the floor, parallel to my A/V cables and as far away from my power cables as possible (limited space in my apartment).
Is it probable that the better, cleaner sound heard on the 16 gauge wire is a result of the difference in wire gauges, and perhaps due to the fact that the 16 gauge wire is better constructed and insulated? I noticed the 12 gauge wire looks more bronze colored, almost has a dirty look to it, where the 16 gauge exposed wire is bright and shiny. Are all speaker cables really created equal? Any thoughts/suggestions would be greatly appreciated.