You compiled the drivers using incorrect kernel headers I think, really use the correct ones.
On the other hand I wouldn't even use the nvaudio kernel module. In the past this driver was really needed. After the driver release everyone could see that the nvaudio driver is just a modded i810 audio driver. The only changes include that the output messages don't output i810 but some nvidia stuff and that the driver includes the nvidia pci id.
Since months the normal i810 audio driver contains the nvidia pci id too so you don't need the nvidia audio driver.
Just use "i810" likely that driver is also more recent and bugfree.