Receiver

+2 Anthem

Am I doing something wrong? I have a 65" 4k TV and tube amps in 2 channels with a sub...

Another way to go would be to get separate pre amp processor and multi channel amps.  I use a Parasound 5 channel amp in one system and the Anthem MRX 520 is basically a preamp.  In my other HT system the Anthem 520 drives all speakers.  Miller’s remark that a receiver might have to much going on under one bonnet is an extension of the same philosophy that in two channel, separates work better than an integrated amp or amp/DAC; there is something to that but in practice there are excellent sounded integrated amps and AVRs

Separates DO work better! Its just that you have to go very, very far up the food chain for that to be the case. Where money and value are concerned, that is where integrateds really shine. 

The main difference is that with a stereo integrated amp you can at least achieve higher performance with separates as long as you are willing to spend a lot more money. Where with multichannel there is no amount of money that will buy you as good quality sound as you can get from something as relatively affordable as say a $3k Raven Blackhawk.  

With a setup like the OP has, and assuming a very limited budget, the smart thing to do is first answer the all-important question: What matters most to me, really? And I mean REALLY???! 

Because if it really is sound quality then the answer is stereo and the value answer is an integrated amp. But if it is "Surround! I must have surround! And 7 channels! I want HOME THEATER!!!" Then in that case forget about it. Might as well stick with the AVR. Do Whatever. Just don't kid yourself about sound quality being a priority. Its not. Its for movies. Its a visual medium. And everyone making components for HT knows this, they know their market, and they pay just enough lip service to dupe buyers into falling for what they all want to believe, that they can have it all. 

The first 5 channels are probably the most important in a home theater.  Actually, the front 3 channels are the absolute most important (center channel being the primary).  The surround channels are not necessarily required, but they definitely add an ambience to the experience and they will make the sound bigger.   Beyond that, it becomes almost a gimmick game.  I have been in Atmos theaters with tons of speakers all over the place.  It's interesting to have sounds flowing above you, but I can still hear the flaws in their speakers/amps/electronics.  I'd much rather have the absolute best 5 channel system I could do instead of a 14 speaker immersive setup.