Same probleme here, I installed AmpliTube Custom Shop Version 4.2 for Windows (I am using Windows 7 together with an M-Audio ProFire 2424 and an Axe FX II).
As soon as I start AmpliTube 4 it says it could not initialize audio device because input and output devices dont share a common sample rate.
But as soon as I then enter "Audio Midi Setup" and select any of the provided Technology options, AmpliTube crashes/freezes.
I tried Asio4All also (however I dont want to use it because the native drivers work fine with my Steinberg Cubase Artists 8), but none of the options work.
I was considering buying an iRig 2 HD to use it together with AmpliTube 4 in the living room thats why I initialy wanted to try AmpliTube CS 4. But those crashes dont make me confident that this is a stable product, at least for using it on the laptop?