Getting the most of the sound out of my speakers?

I have sunfire ribbon speakers,the front two are CRS-3(80Hz-40kHz
Power Handling 25-440W
Impedance 6ohm (nominal)
Sensitivity 90dB
SPL (max.) ,center CRW-3C(Frequency Response 80Hz-40kHz
Power Handling 25-440W
Impedance 6ohm (nominal)
Sensitivity 90dB
SPL (max.) and two backs CRM-2BIPFrequency Response 80Hz-40kHz
Power Handling 25-400W
Impedance 6ohm (nominal)
Sensitivity 90dB
SPL (max.), runing them all with DENON 3312 receiver ,I am new at high end settups meaning I do not know much about preamps,amps,processors...so the question I have is how can I improve my settup,what would work best with these speakers and the most important is it worth it going with this improvement considering the expense,thanks for any response