Hello!

I have a vintage Harman-Kardon 800 receiver that I inherited from my grandfather. It works beautifully and sounds wonderful paired with two Advent loudspeakers of a similar vintage. However, this is only a stereo receiver (well, technically it's quadraphonic, but good luck using that in 2021), and for the last few years I've been living with roommates in a house with a 5.1 surround sound system, and I think I'm going to miss the immersiveness of the sound.

For reference, here's the best picture I can find of the rear panel of the 800 (mine is in storage right now): https://www.usaudiomart.com/details/649420788-harman-kardon-800-quad-receiver/images/1815084/

So, I'm moving into a one bedroom apartment, 700 square feet and change. If memory serves, the living room is 11 x 14. I'm likely going to pick up a Sony X90 from Costco since the 55" is $960 right now unless there's something really good and cheap you'd all recommend (I can't find the TCL stuff locally anymore for whatever reason). Part of me is thinking I'll also get, at some point, a 7.1 receiver and a 5.1 speaker system, likely the Klipsch reference series due to its price (I'm flexible, though, and I note that there's an entire flair tag for "Klipsch Again?")

What I would conceivably do is run the 800 and the Advents as the two front channels, and then, when required, run the rest of the 5.1 speaker system as the other speakers out of the 7.1 receiver, maybe splitting the signal between the two receivers depending on if I wanted stereo audio (or to just listen to music) or surround sound. As a bonus, if I got a Denon HEOS or similar system, I could put satellite speakers around the apartment for whole-home listening, conceivably.

However, since I know very little and you all presumably know more than me, I figure I will ask the experts. Is my plan feasible? How would you accomplish it if so? Or, do you have a better idea as to what to do with this wonderful piece of hardware? I would not consider myself an "audiophile" but I am a big music listener as well as a musician and I pretty much always have music playing in the background.

Thanks!