Hi all,
Seven years ago my wife and I purchased a 1907 Masonic Temple building in historic Kerby, Or, on the west coast of the US. We remodeled and restored the building into my studio and gallery on the first floor where I design and hand craft fine furniture (http://jerrywork.com) with our living quarters on the second floor. The 1500 square foot room that was the Mason's meeting room on the second floor is now our living room, dining room, kitchen - great room. It has 14 foot ceilings with large plaster coving at the top, arched windows with stained glass inserts and 100 year old clear fir floors.
For a sound system we selected a B&O 5500 that is buried within a cabinet and controlled buy a 5500 MCP talking via direct link cable with a two way direct link IR wall unit. There are four hidden ceiling mounted JBL 10" pro plate speakers in the four corners of this large room. A 12" 150 watt powered NHI sub wolfer is hidden from view. The sound is fantastic for most, but not all, music sources. Our US local Peoples Republic of Jefferson Public Radio (broadcast from a small regional college radio station) so hypes the bass that to listen to it at all requires turning the NHI system off. A blues or jazz tape played through the 5500 tape player sounds great with the sub at about 50%. A CD of the same music requires the sub at 25%. An MP3 or 4 rip requires more bass. So, in a large room with lots of volume, the sound changes dramatically with the music source. Strange as it sounds, our favorite source is old commercial tapes.
Now, all this said, we are both 69 years old and our ears would not be called "reference quality". Two of our sons are professional musicians, however, and they confirm our preference. Their ears are "reference quality".
In the library and guest suite on the same second floor, a 700 square foot room with 10 foot high ceilings, we like the 4500 system playing through passive 120-2s. There is an 8000 system on the way with the very large passive speakers of that day and I will report what that sounds like when it is up and performing properly.
Bottom line, from our experience one cannot make a generalization about the benefits or detractions of a subwoofer, powered or not without taking into account the room, the ears of the listener, and the music source. Hope this helps.
Jerry