Exactly what you need!
This allows me to use my effects floorboard (Line 6 HD500X) to switch channels on my amp. For example, my Egnater Vengeance's footswitch has the following buttons: Channel (clean/dist), Mids1, Mids 2, Effects Loop, Reverb, Master 1/2. I no longer need my footswitch, it can all be controlled by hooking this bad boy up to my amp and my Line 6 pedal. Use a floorboard/MIDI controller to run into the Amp Gizmo and the Amp Gizmo has a special cable (not included) that runs from the Amp Gizmo into your amps footswitch jack(s).
A special note: my special cable for my amp is 1/4" TRS, meaning that it is stereo. I.e. A typical 1/4" cable (like a guitar cable) with the black ring half-way up the tip. This allows each 1/4" to switch two different things from the same jack if that is what your amp requires.