Pops & G13 have both expressed my sentiment regarding the SR Master Couplers. Despite other improvements, I experienced considerable thinning of the bass region with those particular AC cords when I tried them. I also have one SR Reference AC which works much better as an all-around cord. Right now it's on the CD player, but it might be found connected to any of various components, or none at all, depending upon my setup. Their next better cords (the Resolution Reference AC, & Designers Reference AC) did not do so well for me but again that is all system-dependent. However their best cord, the Designers Reference Squared AC, sounded so good that I had to buy another one.