Just posted this in another thread about an Anthem unit (where it is failing)
https://www.audiosciencereview.com/forum/index.php?threads/review-and-measurements-of-anthem-mrx-520-avr.8961/ ....believe they have reviewed a few other Anthem units so you might look around a bit there. I doubt there's significant difference in processing among their units, tho.
I doubt you'd hear anything particularly different from your current unit, except the differences between their different eq/dsp software (Anthem Room Correction vs AudysseyXT if you use such and if that may be worth it to you to change). Personally I don't buy into Anthem being superior generally (altho Anthem Room Correction generally gets good remarks), and their pricing is higher than equivalent units from the likes of Yamaha/Denon/Marantz as they aren't able to take advantage of economies of scale as well.
The audio issues you describe could be due a variety of things, perhaps speaker, sub integration or even sub placement/room modes, which a second sub could help resolve; I'd probably get the second sub and see how much that improves your setup first. Sound quality primarily resides in the speakers rather than the electronics.