Upgrading my receiver. Looking for advice.

[ScottiePlz]

My current setup:

Yamaha RX-V371
Klipsch RP-8000F (left and right)
Klipsch RP-504C
Klipsch Reference R-112SW
Turntable: Rega Planar 3 running through a Project preamp
TV: OLED LG

My receiver is the oldest piece in my setup. I'm curious how much of an upgrade I would see if I bought something better. I don't use the HDMI ports on my receiver. I only use an optical cable, so that part doesn't bother me. I'm really looking for an upgrade in sound quality, and being able to add another subwoofer down the road. Let me know what you guys think.

 

[ScottiePlz]

For example, would the Onkyo NR696 produce a noticeably better sound than my RX-V371? I would ideally like to stay in the $500-$1,200 range.