Auditioning had a huge affect on my potential budget

Yesterday I went to my local hifi shop to audition some gear as I'm looking to upgrade my home theater from my an inexpensive theater in a box. I had gone in thinking I would spent about $1500 total and have a pretty nice system. The employee working there was super nice and let me audition a ton of speakers and receiver combos... Even some equipment that's well beyond any budget I could hope to put together to help create a full context of gear.

The system I am looking to build is a 2.1 or 3.1... Surround just isn't my cup tea. I also wanted a receiver capable of switching between multi-channel and stereo for video vs music listening. I was shocked by how much the receiver really affected the sound. We started with a Marantz 7.2, then she showed me a Yamaha stereo model, an Anthem 520, and then a tube amp I didn't get the model of as it was five figures. I was blown away by the difference in sound stage between the Marantz, Yamaha, and Anthem... The Anthem was the clear winner the depth it created in Pink Floyd was like nothing I had experienced.

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. 
I am becoming a fan of Anthem HT too, make sure you are comparing apples to apples. That is, if Anthem had a processing mode turned on, make sure you know which one, so you get it home and use it. :)
Two channels can be great for both music and movies.Just add a sub for watching films with explosive special effects:)
Dude, you've barely scratched the surface and you clearly have the open mind to appreciate the differences. PLEASE go to a few high end shops and listen to their 2 channel audio systems before you buy. I mean the stores that sell mostly brands that the general public never heard of. Most of them have more modestly priced gear like the the Anthem you enjoyed, that will open your eyes and ears. 
Long ago I learned that I wasted about $30k on a big home theater rig that would give me barely any more enjoyment than a bluetooth box speaker since I'm watching football, comedy, news, etc. Invest the bucks in the 2 channel audio for your music, that's where nirvana lies for many....Just my take, Cheers,
You said surround isn't your cup of tea BUT your looking at Multi Channel Surround Receivers?Do you listen to a lot of FM Radio?If not you want to look at a 2 channel Integrated  Amplifier...How big is your listening room?BIG speakers in a small room no good & vice versa..How are the acoustics?Lots of hard reflective surfaces will cause a brittle sound,heavy carpet with drapes & overstuffed furniture will sound like the music is in mud...
2 channels stereo amp will be always better than HT receiver .I had before 7.1 HT system but got rid of it and moved to hi end stereo system everything sounds much better now .