MXR M - 103 Blue Box is a quite interesting pedal. Unfortunately I haven't really found any use for it. It's a really easy to use pedal with only two knobs. Unfortunately the features aren't that great. There is just a blend knob and a volume knob, which means there is just one knob to control the octave effect and the fuzz/distortion effect. The sound is pretty good, but you can't get a clean or a cleaner sound together with the octave effect. Whenever you use the octave effect the sound is very distorted and it's quite hard to actually separate different notes, because of the heavy distortion and fuzz, additionally you can't hear any chords unless you turn the blend knob up, which means you don't actually use the octave effect. So if you turn the blend knob up then you won't hear any of the octave effect and if you turn it down then you only get a very weird, dirty and muddy octave sound. If you turn the blend knob to the middle you will get a mixture of the fuzz/distortion and octave effect but it's still very dirty and muddy. It works quite well though as a dirty fuzz pedal when you have the blend turned up. Unfortunately this pedal didn't meet my expectations.