2 subs connected to a 2 channel amp?

Yes...joining the positive REL wires and plugging 'em in the back of my amp. RELs use a 100,000 ohm signal each so the amp has no idea they're connected, and the damping factor of the Pass XA-25 is 500 so that is still in play...more bass control supposedly. Also works fine with my single ended tube amp.

I use 2 RELs with the cables joined in banana plugs (the positive joined, and the 2 leftover negative leads into left and right negative terminals) with the main speakers using spades. Subs of course are mono which does not matter...Works great for years with various amps.