I don't know if going to Arx or EMP Tek from Axiom is a big upgrade, but one thing is for sure, you need to get a matching front stage speaker set. From what measurements I have seen of Axiom speakers, I wouldn't be surprised if Arx, EMP, or Ascends were an audible improvement, but I can't believe that improvement would be gigantic. If it were me, I would upgrade to such an extant that the improvement is immediately and unquestionably noticeable. I would save up and skip all these mid fi towers and take the system to the next level, I would go for Pi, JTR, upper end JBL LSR, Seaton, etc. If you don't need huge dynamics, I would be looking at Philharmonics, Salks, Ascend Sierra 2s, and speakers along those lines. You might also look at the some of the better studio monitors, Mackie HR series, Adam AX series, and Emotiva Stealths look pretty good too. I think any of those would knock your current setup out of the park and also any of the replacement systems you are thinking about. Yeah they cost 3X as much, but at least you will never be left wondering or feel the upgrade itch after that.