Sadly, no lines currently available on the market are actually pH perfect. Our line is pH stable meaning that after it's mixed into a solution, the pH won't fluctuate, even after 2 weeks of sitting stagnant.
As for self buffering, it's simply impossible. If a nutrient solution has a stable pH and water pH is variable (based on where the water comes from), then the water quality will always have an effect on your post mixing pH. You may land right on that sweet spot, but more than likely, you're going to have to buffer.

praise the Gospels of Factual reality on this Joel!

I have a small permanent dent in my forehead from the cinderblock of endless repetition about this--

, at the Infirmary especially,... soil/soilless growers in particular seem to equate this with actual in-pot pH buffering and management, and I tell them that it just doesn't work like this once in there,
only when in solution! Too many other influencing factors, and the capacity of the solution buffering is too weak to deal with it all,.. there is no set-it-and-forget-it with pH in these circumstances,... Something I wish the manufacturers would actually state clearly in the instructions-

But you know how it goes, some get away with it
by sheer dumb luck, and then they think that's the norm'!

--
thanks Joel!