I've sampled every Alnico grade there is, but none of my suppliers had something they called A7.
However, there IS an Alnico grade officially recognized by the MMPA, called Alnico 5-7, and that's what I think the Aria verbatim was referring to.
I've sampled this particular grade from four different suppliers, two Chinese, an Italian and an American, but it was *not* of *my* liking. It had a lot of power, but it sounded harsher and even more "scooped" than the "normal" A5 grade. YMMV.
There you have it!