I just got the iRig Pro and it worked great on the iPad Pro but it wasn't so great on my new iMac.
It didn't matter what app I was using iRig Pro with, the input gain was way to high and the built-in gain knob wasn't controlling the level.
Standard troubleshooting steps dictate that one of the first things to do is update the firmware. I found and downloaded the iRig Firmware Updater 1.6 from the IK Multimedia user area but it crashed when I tried to run it.
Snooping around the IK Multimedia user area I also found 1.7 Firmware Updater. I could not find an explanation on the why the website has two versions of the Firmware Updaters.
I downloaded and ran the 1.7 Updater and immediately ran into a permissions failure.
Time to Postulate
My iMac is brand new and it is running the most recent version of Sierra. There should be no reason to for my system not to be able to run the Firmware Updater. I'm not having any crashes or performance issue from other apps so there is no indication that the software failure is from Sierra.
It is possible that both Firmware Updaters were not compiled for the OS updates for Sierra. It would explain why I cannot run them.
In situations like this, sometimes running the actual program inside the app package yields positive results.
I right clicked on the firmware updater and selected "show package content".
In the OSresource folder, I found the actual program and double clicked on it.
Violà! Terminal automatically launched to run the app but the update was successful. The iRig Pro now works as expected.