My visit to player99's humble abode netted me some homework. One of the pedals he asked me to fix was an Xotic Effects X-Blender. Interesting pedal, in the same vein as the GigRig Wetter and similar from Earthquaker and Empress. It allows you to introduce or bypass a second parallel path, and blend between the original input signal and whatever you have plugged into the send/return loop. On top of that, the polarity of the loop signal can be inverted, and there is a switch-selectable boost function with very effective EQ for the loop signal. The big knob allows for blending/mixing loop/wet and input/dry. If you simply run a patch cable from send to return, and set the mix knob to 100% wet, the unit can be used as a simple clean booster. Running a chorus in the loop, turning on the boost function, bumping up the treble and turning down the bass, allows for a nice crisp chorus to be dialed back a bit instead of being in your face. If one inverts the loop signal, setting the mix/wet-dry knob in middle-ish positions can get you varying degrees of cancellation. All in all, an interesting and useful pedal, as I'm sure all the variants made by other companies are as well. My own DIY units provide a 2-out/2-in splitter/mixer arrangement with a stompswitch to completely bypass anything external. The two return feeds can be blended with individual level controls rather than a master blend knob. I add some gain to the mixer stage so being able to use the full rotation of a pot to pad things down is helpful. Having the dual loops is useful because sometimes the sound you want to make requires parallel processing in two fashions. For example, I could send one feed to a fuzz and a second feed to a delay. What I get to mix together is a clean delay sound and a non-delayed fuzz sound. The stompswitch allows me to cancel the whole shebang in one move. That's not better or worse than what the X-Blender does, just one more set of possibilities. These are useful devices.