I have Arc connected to a Sony TV and two Sub (gen 3s). The Arc and the Subs are on the same wall as the TV. The Arc in the center, below the TV and the 2 Subs left and right of the Arc (about 6’ left and right of the Arc.
Once in a while I hear what sounds like a low frequency thump or two (kind of like distant fireworks).
I don’t recall this until I added the 2nd Sub. Thoughts?