Like everyone, I've been unable to use the IO26 since upgrading to El Capitan, however I found a workaround yesterday.
I've determined that the issue is due to the Alesis kernel extension for the device being rejected by the El Capitan's new "System Integrity Protection" because it is unsigned. Until Alesis releases a signed version of the driver, here's how you can disable System Integrity Protection:
1. Reboot your machine in recovery mode : hold cmd+r
2. Launch the Terminal from the utility menu and deactivate the System Integrity Protection status by entering the following command line :
3. Reboot the computer