I'm too inexperienced/old to tell the difference. I'm always hearing from others the highs are different or this sounds muddy, etc. but honest to God I cannot hear it. I am listening through Yamaha HS-8 studio speakers, but to me, I cannot hear the difference. I wish I could. I am 70, although my ears are still good, and have not been blasted out over the years. I always keep my firmware totally updated and have great guitars. It probably is my lack of experience. I played a lot when I was in high school back in the 60s. Took up guitar again two years ago in retirement. I play/practice everyday, but I guess my ears ain't what they used to be. My props to Cliff and all the great people at Fractal. I love my AXE FX III, but I honestly cannot hear much of a difference from 15.xx to Cygnus.