The room will change once you add furnishings and carpet. For a short time I had a 350 in my 8,000 cu ft room and it did an "ok" job, but nothing like the 500 or 600.

Also, you may find that a different position, other than the corner you tested, will be the best spot.

M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85