I've got an Alesis I/O 26 that won't play but 1 side on the output 1 & 2. I've tested the drivers for the PC, and they play fine. When I use the Win7 test it sends a signal to both sides, and I see both on the meter in the Windows Configurator, but it only sounds on 1 side, regardless of how I connect the jacks. Also, when I look at the H'ware Direct Monitoring it only shows 1 side getting signal. I've reinstalled the driver, AND even tried to re-install the old firmware. The reason for trying to reinstall the f'ware is cuz I connected my Alesis 8HD keybd in the 1st 2 inputs, but the LED's are lighting up on Ch.s 1 and 8 only.
Tomorrow when I have access to my nice S/PDIF cable I'm going to try that output on the I/O 26, and INTO the S/PDIF on my PC. I don't have any headphones with me that will fit the jacks I have available.