Parasound A-23s in mono or A-21

I currently have a Parasound A-23 and have upgraded my front l/r speakers to B&W N802's. I feel that I am now a little underpowered and will be looking to upgrade my main amp. I am looking at two options both would be in the same price range. First option would be to purchase a second A-23 and running the two in mono and the second would be to get rid of the A-23 and go to an A-21. The concern I have with two A-23's is that they somewhat discourage against using the amps in mono on speakers that go below 8 ohms. The B&W's state that they can dip down to 3 ohms. The A-21 has advertised specs at that load, unlike the A-21's in mono.