Yeah, you have a pretty good-sized room and a fairly low-powered AVR -- not an optimal starting point and will limit your speaker choices, especially at your price point. Case in point, although all very good speakers I wouldn't recommend any of the four you found in your A'gon price search as they are likely too much of a load for your Marantz to drive them optimally (or even effectively) in your room. IMO you should focus on speakers with upwards of 90dB efficiency and that don't drop much below 6 Ohms in impedance, generally speaking. Since you said you're not a bass hound, at your price point you'd have many more choices if you expand your search to include monitors.
That said, there's a pair of Silverline Audio Preludes for sale on USAudioMart for $800 that might check all your boxes. Off the top of my head, some other brands that might work well with your AVR are Joseph Audio and ProAc if you can find any that meet your requirements. Hope this helps, and best of luck in your search.
That said, there's a pair of Silverline Audio Preludes for sale on USAudioMart for $800 that might check all your boxes. Off the top of my head, some other brands that might work well with your AVR are Joseph Audio and ProAc if you can find any that meet your requirements. Hope this helps, and best of luck in your search.