A different perspective - your room could be the real problem. 18x16 is almost square (bad) and a ceiling of 20 makes damn near cubic (very bad). The centre ridge might save you, but I wouldn't count on it.
In these circumstances, I would absolutely begin with speakers, Ralph's expertise notwithstanding. Your room effects look to dominate everything else. Consider real room-filling speakers, like the big Magnepans. Run them on $1000 solid state if need be, until you can afford to improve your electronics.
Can you audition somehow? Because that may make all the difference.
Just my opinion.
In these circumstances, I would absolutely begin with speakers, Ralph's expertise notwithstanding. Your room effects look to dominate everything else. Consider real room-filling speakers, like the big Magnepans. Run them on $1000 solid state if need be, until you can afford to improve your electronics.
Can you audition somehow? Because that may make all the difference.
Just my opinion.