Hi all TB-ers, I just received a MXR M87 this afternoon after about 2weeks waiting. The first thing I would do with all my just-received pedals is to open them up, this MXR is not an exception. And I found a little switch inside of the pedal, I also tried 2 positions of it and this is the result: - The upper position - the default position of the switch, sounds more normal and the gain reduction lights work as usual. - The sound of lower position of the little switch seems to be louder but there is no gain reduction lights. So this is my question: can anyone tell me exactly what the function of the little switch is? As I said, i found some difference in tones of those, but can find the way to describe. And it's not mentioned in the manual user. Right now, I'm setting it in the default position. Thanks for the answers, Bros. Have a nice day!