I started a new room a while back and had to stop because I got hurt, about to get back on it as the foundation is finished. The room interior dimensions are 18x30 with 12 foot ceilings, the low freq limit for those dimensions is approximately 30Hz. Currently running a single 15” sub on left & right channels (I make rekkerds), will make new two 15 subs to go with the B&W mains. This will be one room, no separate control & tracking room. With Pro Tools and an iPad running the Avid Control software and headphones with a mic you can get right in with the musicians and produce as you should, a little more intimate setup. Plan on making this more like a living room environment with couches and other comfortable surroundings. Nothing wrong with a one room approach.