+ big_greg, well said.
mijostyn continues to take the time to share a great deal of his practical experience gained from his interesting system and room relationship. Also well done. I have great admiration when it comes to his immaculately dust free well appointed shop. Absolutly stunning.
IME, if one uses the simple crawl test and low frequency test tones to locate their rooms best sounding room mode. Positioning even a modestly priced -3dB subwoofer with basic controls in, can have quite an entertaining low frequency presentation at least at the listening position. Cost? A long pair of economical interconnects.
With the exception of a four sub array, I've found poor room positioning to be the most common reason for poor subwoofer performance.