I have done this, and I came to the conclusion that, a few things come before sound quality..
1- aesthetics, if the best place for your sub is in front of a fire place {happened to me} you are better off finding a new spot...
2- Comfort, if the best place is where you keep your ottoman that you normally put your feet up onto, you are better off finding a new spot...
3- Access, if the wire runs to a corner behind the couch, and the sub sounds better 9 feet from there the cable will have to cross a floor, then find a new spot..
When I built my house I put the subwoofer rca panel in the corner where I new I would have no furniture, it sounds good there but when doing "the crawl" I found that in front of the fireplace almost center of the room was the best spot sound wise... Needless to say my sub is in the corner where I wired the panel and have no furniture... Speaker placement is key to sound quality but for me it comes in after a few other factors...