Any quality receiver is going to have binding posts to insert ordinary speaker wire and tighten. Then you can use a number of speaker choices (either Onkyo's own brand or even better, speakers from dedicated speaker companies like Polk, Energy, or Infinity, etc.) Both Onkyo and HK are good makes.
The Panny speakers could probably be made to work with some wire clipping or some such, but I wouldn't recommend it. I'd just get all new speakers and a new receiver. (Yes, I realize you want to save money, but IMO it's not worth it to use the Panny gear because they've got it set up to not work with other makes.)
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