I've seen a few old posts about this while I've been figuring out how to set this up after buying an IRig Stomp I/O to use as a stand-alone MIDI interface, I'd like to say it is possible with a little fiddling.
I assume it will work for Axe I/O also but I can't be certain as I don't have one.
This assumes you want to use the Stomp I/O as a stand-alone MIDI interface on a PC with the Axe I/O One (I have no knowledge of iOS Devices).
Cables Needed: Midi In and Out & Power Supply For The Irig Stomp I/O.
(No USB cable is needed for the Irig Stomp when using as a stand-alone midi interface as having it connected just seems to confuse Amplitube).
(Note your IRig Stomp I/O will not be shown in the control software or AmpliTube when using it as a stand-alone midi interface)
I am using AmpliTube 5 in this example.
1. Axe I/O One connected to your computer the normal way with the USB cable.
The Axe I/O One with Midi-in to Midi-out on the IRig Stomp and Axe I/O One Midi-Out to Midi-In on the IRig Stomp.
2. Plug your Irig Stomp Power Supply into your Stomp I/O (DO NOT TURN THE POWER ON YET).
First, hold down the far left pedal button (the first one) on the IRig Stomp then turn on the power to your Irig Stomp while holding the far left button down.
(The IRig stomp will now go into stand-alone mode and the pedal lights will flash 3 times then the stomp mode light will illuminate along with the gain and volume lights).
Your IRig Stomp is now in stand-alone mode and will stay in this mode until you repeat the above process.
3. Open Axe I/O control software, if not already running then load it up and click the controller option in the control panel.
Set Double Switch 1 and 2 to Latch Not Momentary this will make it able to turn your pedals on and off in Amplitube and the expression pedal should be set to linear.
(leaving switches 1-2 on momentary seems to make them still attached to the expression pedal I'm not sure why)
Then set the Switch 1 CC# to 64 and Switch 2 CC# 65 Set Your Expression Peddal CC# 12
(These are the settings stated in the Irig Stomp Manual)
(I am not sure if you can make more than 2 Switches work as I can't find an option for more than that in my Axe I/O One software).
4. Load Amplitube and click the settings tab on the far right, Make sure to have Technology set to ASIO, Input device - Axe I/O, Left Channel - In1, right channel blank (unless using stereo input). Output device - Axe I/O, Left channel - Out 1, Right channel Out 2, Buffer size (whatever works best for you, lower = less input lag but possibility of pops and noises).
Under midi input select ANY or Axe I/O then close the tab.
5. Load your preset and select your pedal (ie: Wah) right click your pedal in the top screen and select Assign midi - wha - click learn wha, when the box appears saying waiting for Midi input press your expression pedal on the stomp I/O. (you should now be able to control your wahwah with your stomp I/O).
With stomp pedals right click your pedal of choice - Assign midi - bypass - click learn bypass then tap the stomp button you want to use on your Stomp I/O. (you should now be able to turn you pedal on and off with the Stomp I/O.
This took me a while to work out but I hope this helps some of you out and make use of that old Stomp I/O as it works great for me with my Axe I/O One.
