You can still find the Onkyo tx nr 797 for around 800 I have the tx nr 787 an older model running a 5.1.4 system and it has been fantastic. Onkyo does not have any new models I currently see which is unfortunate because they were pushing affordable 9 channel av recievers. There is no question idf i neede a 9 channel reciever I would have zero hesitation buying the 797 vs higher priced marantz denon etc. It has worked flawlessly for me.
A little over a year ago, the 787 was available at a price that forced me to buy it even though I had no plans to upgrade my existing 7.1 system and was convinced that ATMOS/DTS X was a gimmick. After sourcing out matching speakers for the height channels and using ONKYO's improved setup procedure, I fell deeply in love with 3D audio.
It's a dual edged sword. Like GOLFA (garage), I had limitless placement possibilities in my basement setup. I opted for a 7.2.2 setup with middle heights. I sought out as much ATMOS content as I could find and went back into my catalogue and tried upsampling many titles with the amp's built in DSU. IT WAS AWESOME!!! ...and of course led to questions like -If two height channels are good, would 4 channels be better? If ADVANCED EQ is this good, can AUDESSEY be better?
In December, a DENON X4500h came up on Amazon warehouse at a price that once again forced me to buy it. With external amplification, I can now support 4 overhead channels and have fallen down the AUDESSY rabbit hole. I've answered my questions definitively.
My advice to GOLFA, would be to go the same route. Pickup up a low priced ONKYO for now, save up for the increased channels later. As long as he has the flexibility in speaker placement, he can enjoy 3D audio now and improve upon it later.