If your Pioneer SX1980 has pre out jacks buy a good power amp and use that instead of the receiver's amp. A Crown XLS 1502 is a good recommendation (~$400).
Understanding ohms
I love music but I don’t understand tech and specs. My receiver is rated at 270 watts at 8 ohms and has a limit power circuit that allows 300 watts at 4ohms. I’ve read that my Montis speakers can go down into the 2 ohm range. Does that mean that a receiver rated at 150 watts that doubles at 4 ohms is equal or preferable to my SX 1980