I have owned both and currently have a PA-7A. The only difference seems to be an even wider range on the PA-7A per the specifications. But this is in the range of 22kHz so most preamps will cut off below this frequency anyway.
But if your hearing goes up that high you may find an odd resonance on the high end with some interconnect cables. I did not see that problem on my PA-5 and upgrading my interconnects eliminated it on the PA-7A
But if your hearing goes up that high you may find an odd resonance on the high end with some interconnect cables. I did not see that problem on my PA-5 and upgrading my interconnects eliminated it on the PA-7A