Hello, I'm the person that Jfrech is referring to that posted on AA. I haven't heard the 50se and the 31se side by side in the same system but I have heard the 31se in a friends system that I'm very familiar with. I think it would be a fair statement to say that overall the 31se is the more musical pre-amp. For those who have the 50se and are thinking about upgrading to the 51se don't hesitate! I can't think of a better way to improve your system for that kind of money. The sonic improvment is substantial. Good luck, Thomas Colato