most tanks will have a ph of 5-8. the care sheet basically says you can keep them in a ph of 5-8 (any more or less is consitered extreme) and they will adjust and do fine. remember a constant ph is a good ph, altho you need to avoid extremes.
What they are trying to tell you is that a CONSTANT PH is more important than WHAT NUMBER the PH is. Anything in between 6.5 and 7.5 (which is what comes from most taps) will be fine. IF you test it and then decide to change it you run the risk of shocking your fish when doing water changes ect... So the easiest thing to do is leave it where it is at and let the fish adjust to it.
There are some exceptions but p-bass are not one of them