I have A23 amp, which sounded nice, but man it could heat a room. The A21+ must be a who lot hotter. I had a pair of M700s that I really liked, but my Emerald Physics KCIIs are an easy load. If you’re patient you can pick up a pair at a great price
Underwood HiFi was running a special on Audio Alchemy/Elac amps which should be really good options, and more powerful (I think)