randy-11 has it right. I would only add that paying attention to the conductor and dielectric quality as well as connectors on the cables can/do make a discernible difference.
One surprise for me was when I got my Vandersteen Treo CT speakers with their low 85db efficiency, my very heavy gauge "Earth series" cables from Audioquest made with lots and lots of very pure copper lent a mid bass "thickness" to the sound. Moving to Paul Laudati's Clear Day silver cables opened up the sound, ridding my system of that thickness and revealing smooth treble detail that I had believed the carbon tweeters were capable of but I didn't know what I had been missing until inserting the Clear Days into the system.
One thing however, in support of randy-11's statement about efficiency, I had to buy the Clear Days with the most silver, the double shotguns to accommodate to the low efficiency.
