The iPad is the perfect practice tool for guitarists. Because it instantly becomes whichever app you load, it can be a warehouse full of amps, a fully-featured demo studio, a TAB reader and writer, a guitar synth, a scale library, and probably a whole bunch of other thing we haven’t even envisioned yet. But most of these functions are useless with a guitar signal entering the iPad. There are plenty of interfaces for guitar out there, and they all seem to operate in different ways. Some are simple and inexpensive, while others are a bit more pro-spec. That’s where the GuitarJack Model 2 comes in.