I'm pretty new around here, but I've done a lot of reading and actually ended up with almost the exact same setup as you. I grabbed a refurb 2113CI (which was the old version of the X2000) and a set of the Andrew Jones Bookshelves with an RW-12D sub. My speakers get more than loud enough for me with just the two, and I don't even have the matching towers.
Another key component here is speaker sensitivity. The more sensitive the speaker, the less power you need to reach a given volume. A lot less. Going from the BS22 to those Aperion towers you mentioned are a difference of 85db vs 88db, which is like doubling the output power of the amp. The FS52 measure at 87db, so the Aperions should be easier to power than your current towers.
Personally, I wouldn't worry about your AVR until you are spending a lot more money on speakers or have a need for extremely high volume. And you might have to spend a lot for a worthy improvement. Room treatment gets a lot of love around here too, and that might be worth it as well before you go spending $4000 on an AVR in a room with poor acoustics.