Pricewise maybe yes, if that is your focus if it is soundwise no. I tested all three streamers with headphones AND a full hifi set.
I do have to admit the difference was a little less noticable on headphones. But still there. But the moment you go with a full hifi decent speaker set.
But everyone has the right of there own opinion, I know what I have heared, which was not imagined.
The A6 master is a good option if you replace the build in psu with the custom lps one, but then the price is nearly the A8, then the a8 is smarter choice.
There is only one reason why I can understand the choice the a6 or a6 master over de a8, and that is the price. Which is a valid choice if the budget is not there.
Because even the a8 is te best of the three, the a6 for the money is a bargain! All three of them are a middle finger to all other brands that sell streamers overpriced with less functionality imho.