I have the 50 and it sounds really really great, but in this instance you are talking about an older unit that doesn't support 4k or Atmos.
Among multiple processors, including Onkyo and Emotiva, the Anthem 50 was spectacular just based on audio performance alone.
Another feature you'll be missing out on is any sort of EQ, whether automatic or otherwise.
You might want to see how much your unit can be upgraded and/or consider a Marantz.
