You can switch the sub off,..if you hit "ch sel enter" button, flip through to sub, then adjust it all the way down, the final setting is off.
I don't have a 2805,...I do have a 3805. I have not run across this problem,... one thing though, if you have pure direct and analog set you should not be able to use any of the eq settings. Pure direct bypasses all DSP and Video circuits.
Are you using the multi-channel EXT. IN jacks?