Only two of the tubes are for the line stage preamp (V5 and V6). The rest are the phono stage. If the noise is on all inputs (and not just phono) it could be one of these two (or both). If so, you should probably replace them both for balance. You may want to consider replacing them all if they all are old.
Is the noise both channels or one?
It never hurts to have a couple extra tubes, so get a pair and see.