Research and audition - also audition the speakers that seem to
get some bashing - no guarantees that you will not like them.
Your Pioneer is decent for the beginning process. There are good
powerfull receivers out there, and they can be a beginning, if you
are somewhat restricted on budget.
Along with some others on the list, check out Focal, plus PSB and
Monitor Audio.
Also, look at Outlaw Audio
Outlaw Audio Speakers and Suwboofers