Listen to all the great advice given above. You clearly have the ears to be a completely sick audiophile like the rest of us here. You appreciate things a lot of people either don't hear or don't care about. You are absolutely correct that Anthem is indeed a big step above the more mainstream brands. Wait until you hear what truly good dedicated stereo components can do.
If your priority is stereo and you can sit in or near the sweet spot for movies, I think you go with a quality stereo integrated amp and a 2.1 system. If HT is more important and/or you frequently have people sitting off axis during movies, you might need that center channel.
What most people will tell you here is to find the speakers that really do it for you first. Once you know that it will dictate how much power they need and how much you'll need to spend on an amp or AVR. Not sure why you're not into rear speakers. IME, when decently set up the rear surrounds GREATLY enhance the movie experience. Maybe you can even use two or three of your current "box" speakers for rear surrounds and upgrade the front two or three speakers. But, by all means go to some higher-end shops to hear what's possible with good gear in a well set-up system. The good news is that there's so much good budget and used gear available these days that you can get very, very good sound on a modest budget. Tell us your priorities and you'll get lots of great help here.
If your priority is stereo and you can sit in or near the sweet spot for movies, I think you go with a quality stereo integrated amp and a 2.1 system. If HT is more important and/or you frequently have people sitting off axis during movies, you might need that center channel.
What most people will tell you here is to find the speakers that really do it for you first. Once you know that it will dictate how much power they need and how much you'll need to spend on an amp or AVR. Not sure why you're not into rear speakers. IME, when decently set up the rear surrounds GREATLY enhance the movie experience. Maybe you can even use two or three of your current "box" speakers for rear surrounds and upgrade the front two or three speakers. But, by all means go to some higher-end shops to hear what's possible with good gear in a well set-up system. The good news is that there's so much good budget and used gear available these days that you can get very, very good sound on a modest budget. Tell us your priorities and you'll get lots of great help here.