I have a Sound Blaster 16 model CT2230 which has developed a problem playing back 16 bit audio. I bought the board on eBay a month ago and it was working ok until recently. FM music sounds ok, 8-bit audio sounds ok, and 16-bit audio sound ok if I use the low DMA channel, but if I try to play back 16-bit audio using the high DMA channel it is very scratchy like there is static in the background. I have a video here: https://www.youtube.com/watch?v=fWGTh-UlOnk. My normal settings are IRQ 5, low DMA 1, and high DMA 5, but I tried high DMA on 6 and 7 and get the same issue. I have the IRQ and both DMA channels reserved my PnP BIOS settings so I don't think it is a conflict. I have also run the system checks on Checkit 3.0 and it says my DMA controller is OK.

Any ideas?