What is ideal dimension size for a home listening room?


Is it a cozy size, large living room, 10 x 15, 20 x 30, some where in between?  I guess it shouldn’t be square.  Let’s assume ceiling is 7 1/2.  Heard ceiling height means a lot.
emergingsoul
@tomic601 ,  I ordered a swarm system about 6-8 weeks ago.  I'm hoping delivery will be soon.  The dba approach is, at least conceptually, a game changer.  We will see.

@arion,  Good comments.  I've been intrigued by the use of non-parallel walls.  Conceptually, it solves a lot of problems if it is properly executed. I'm not aware of any commonly available mathematical models that provides predictions of modes in non-rectangular rooms, which would give me pause in committing to that approach.  
Google says a 20Hz wave is 17m, or 55.8 feet. Wouldn't the ideal room have to have one dimension (diagonal) of at least that length?
@brownsfan,@brownsfan, 

You are welcome. Looking forward to your results with the swarm system. I have been using the Velodyne SMS1 bass eq for years with two subs and it has been fantastic. Note, I stated years, subs and velodyne are over 15 years old. They are classics now:)