Advice on dedicated room

More than anything else it helps just to keep in mind. No room is perfect, and one can easily spend more on the room than the system.   

Back when I was searching around going to all the audio stores within a couple hundred miles the best sounding system by far was in a room just like yours. Corner Audio, only the long axis was vertical. The room was roughly 15x15 with a ceiling twice as high! Yet he had easily the best imaging, most engaging sound of any store up and down I5 from Seattle to Portland.   

That is the main point I would like to make. Harley has an excellent book, and there is a tremendous amount of information. These things are all about compromise. The more you know the more likely you will be happy with your particular set of compromises. 

Hate to tell you this but at 15x16x8 your room dimensions are your biggest challenge. LxW is very nearly square and almost perfect 2x H. Do the math, work out the modes, you will see they cluster big time. I would do this first before anything and plan accordingly. Maybe you can use a false wall to make one dimension less a multiple and incorporate a bass trap behind it tuned to absorb in the range that is left. This will be far less intrusive and way more effective than adding traps later. 

Do not fall into the trap of thinking more and thicker is always the answer. As already alluded to this only traps and stores energy in the room. Sound energizes all room surfaces. What you want is not so much to try and kill this as shape it in a way that sounds good. Your room is small but if done right will be made to sound more spacious than it is.

This small a room will also make it more important than ever that you use a distributed bass array and Townshend Podiums and Pods for isolation. The DBA will make your small room sound huge, and isolation will greatly diminish the rooms impact on the sound by energizing it less. Money spent on these will far outweigh a lot of much more expensive acoustic treatment. 

If you don't know how to work out the modes then look on-line or get Robert Harley's The Complete Guide to High End Audio. My first edition has step by step instructions for mapping room modes. There's probably faster ways now than a pencil but however you do it just be sure and do it. Whole lot easier to fix it first on paper and build it right than to try and fix it later with a lot of expensive space wasting tube traps.