I agree with what Newbee and Philojet have said.
Out of bias does affect the sound. That being said, it is unwise to say to low or to high. To much room for confusion. Much more appropriate to say to cold or to hot. To cold there is not enough current in the output stage to work correctly. Sound will be buzzy, not clean etc.. To hot can sound very good (unless way to hot) but lots of drawbacks. Tubes wear out much to quickly, the whole system is stressed to much which isnt good.
Out of bias does affect the sound. That being said, it is unwise to say to low or to high. To much room for confusion. Much more appropriate to say to cold or to hot. To cold there is not enough current in the output stage to work correctly. Sound will be buzzy, not clean etc.. To hot can sound very good (unless way to hot) but lots of drawbacks. Tubes wear out much to quickly, the whole system is stressed to much which isnt good.