BIG congrats on paying off your student loans. I also paid off my student loans earlier this year - such a huge relief, but lots of work (always had two side hustles).
I like the idea of the Denon receiver, SVS sub and OLED, especially right now since LG finally has some competition which has begun to drive down the price of those panels. Klipsch seems to be the default for HT systems. Unsure (from lack of knowledge) if there are alternatives that can better the Reference Premiers at the price range. If size isn’t an issue, you’re really looking at value, and you can spend just a little more on a sub, I’d take a look at HSU. Question: What do you mean by piecing together “from a various sources.” If it means what it think it means, then I would stick with the same manufacturer and model with the speakers.