The ATC like lots of power so I think the A23+ wouldn't be a great fit. The ATC P2 is dual mono amp which I like but it is $1000 more than the A21+. I am not sure I like the idea of bridging the amps. You get more wattage but won't there still be an issue with current. Also, if the speakers dip below 8ohms, does it become a problem? The nice thing about 2x A23+ is it would be cheaper than and I could biwire the speakers (but then I am only getting 200W). Or I could stick with the NAD M32 integrated amp I have right now (which is 150W per channel I think) and I can biwire. Short story, I think I am still leaning to A21+ or ATC P2 or sticking with the NAD M32.