Agree with @deep_333 that the Yammy Aventage AVRs, especially the upper models (1080 on up) that have a power transformer are very good. I worked for Magnolia for a spell and got to compare Denon, Marantz, and Arcam driving B&W 804d3s and thought the Yammy outperformed them all in 2-channel. Sound was detailed, transparent, refined, and imaged better than all others with a clearer background and a superior 3D soundstage. I was pretty surprised by this, especially regarding the Arcam. A customer who owned a Marantz AVR had me compare with an Aventage AVR, and let’s just say he was no longer happy he owned the Marantz.
That said, you can try subbing in your A23 and I’m sure you’ll hear an improvement, but you’re still stuck with a mediocre-at-best preamp section in the AVR that will continue to be a significant impediment to better 2-channel performance — hence why we were recommending using an integrated amp. If it’s me that’s what I’d do rather than switching AVRs. I’d think adding something like a NuPrime IDA-8 or the like would yield a huge improvement all around for not much $$$ (probably could use its DAC too). Anyway, hope this helps at least somewhat.
That said, you can try subbing in your A23 and I’m sure you’ll hear an improvement, but you’re still stuck with a mediocre-at-best preamp section in the AVR that will continue to be a significant impediment to better 2-channel performance — hence why we were recommending using an integrated amp. If it’s me that’s what I’d do rather than switching AVRs. I’d think adding something like a NuPrime IDA-8 or the like would yield a huge improvement all around for not much $$$ (probably could use its DAC too). Anyway, hope this helps at least somewhat.