I 2nd the motion.
I had a 500 and it kicked....
I recently acquired a 600 and my room is nowhere near the size of your room. My room is much smaller...yet I still enjoy the bass.

Go with a 500 if your budget permits..and heck...if you have extra dollars (which none of us do) then buy the 600.

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Denon 4308
M80x2,VP150,EP600,4xQS8