Hello everyone.
My name is Domenico and I have a question to ask.
I play the guitar by connecting it to the iPad on which I have installed midi guitar 2 and iRig Blueboard; Is there a possibility to control the mix knob (in master section) with an expression pedal?
Thank you all in advance
Hi Domenico!
Welcome here! 
For the desktop version of MIDI Guitar 2 that is possible with the “MIDI learn” function. There is no such function in the iOS version however. So, no, sorry to say!