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.
another option could be to vertically biamp with 2 A23s. I'm not familiar with your speakers but I've had better results biamping one of my speaker systems than using a higher power amp. I would not monoblock the A23's - go with the A21 instead.
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When I tried bridging,I always had a little sound quality loss with other brands of amps.If it was the same,4 ohms would still be acceptable.
In my system an a21 was better in every way by a very noticeable amount then 2 a23's no matter how I set them up. I agree with the others. Go with an a21.
Dig deep and get pair of JC-1's used.
Hi I personally Own an A23 myself and think its a great amp, I have talked to my local "Audio god" who actually happens to sell parasound and asked him this question.

The circuitry is the same just a larger version and I would actually be better off with 2 A23's than one A21 as they shine best as monoblocks and give out 400 watts as oppose to 250. Just thought id pass the info along
I also own a pair of A23s, each used in stereo mode since I have multiple speaker pairs. I think the A21 might be the better choice. Although you may get more net WPC with the A23 in mono mode, current delivery on the A21 is 60 amps, versus 45 amps for the A23. I would give Parasound support a call. They are an absolutely fantastic and helpful company from the owner on down. They will give you sound advice.