I was in need of an A/B switch for my Tophat Supreme Sixteen and after doing some poking around on the internet, I decided on the Little Lehle as a good solution since I don't need to run both channels at the same time. I had to send the unit back and here's why: When you step on the swich to go from A to B, the signal is re-routed as soon as you press down on the pedal. But when you want to switch from B to A, when you step on the switch, nothing happens until you release the switch. So if you're used to switching sounds on a downbeat, nothing happens until you release the switch, and the tone change happens after you intended it to. You can time it correctly by stepping on the switch early and releasing it on the beat, but I don't have any extra hard drive space in my brain to remember if I'm going from A to B, or B to A. Singing and Playing and simple switching is plenty to worry about. No complaints on the quality of the unit, but I downloaded the manual before I bought the pedal and nothing was mentioned about the way the switch works. I'm sure I'm not the first one to return the switch for this reason and I felt a little misled. I ended up building the A/B switcher on the Fulltone site and it works great. Anyhow, just a heads up.