If money isn't that much of a concern for you, I think the AS8 won't be a bad option for the A2. I say this because I had the AS8 for a few weeks with my current A5 and it sounded pretty good. If I had to be very nit picky, the bass from the AS8 could've been tighter, but overall, it wasn't too bad. But I did end up replacing the AS8 with the HSU STF-1, which I have to admit does sound much better (the bass is far tighter and it just sounds amazing). The main reason I replaced the AS8 with the STF-1 is because I felt that the AS8 wasn't worth the price for its sound quality, since the STF-1 can be bought for the same price but sounds much better. However, in your situation, I think the AS8 may be a great option because the AS8 easily connects to the A2. I don't think the STF-1 will connect with the A2. If it does, then I think you'll have to jump through some hoops to do so. I say this because even connecting the A5 to the STF-1 wasn't as easy as you'd think. I had to purchase a custom made cable from HSU to connect them because the STF-1 has a mono sub input, not a stereo input (so I had to buy a special custom cable from HSU that sums up stereo to mono. Using a Y cable won't be as good because that would split the sound, not sum it up, though the difference in audio quality may be unnoticeable because bass is for the most part unlocalizable).
Anywaaaay, getting back to the point, I think the AS8 will save you a great deal of research and it sounds pretty good. The main issue I see with buying another subwoofer for the A2 is the connection problem that I'm sure you'll face, since the A2's don't have a sub out. But kudos to you if you can find a way to connect them to a sub that's far superior to the AS8 for a much cheaper price!
