@salvatore-di-piazza An update - I put a volume pedal in between the iRig HD 2 and my amp, and I'm very happy so far with the results. The volume pedal not only lets me silence the noise of switching between presets, but also lets me adjust to different volume levels between presets. And, I can also use the guitar volume knob to affect the amount of breakup in the amp preset. Looks like a very workable solution.
Yup. Sounds cool. I'm glad you've found a solution!