I have a Crown XLS2500, driving my difficult 4ohm nominal speakers... not all amps sound good with those speakers as they have an impedance drop down to 1.6 ohm - which causes many amps to misbehave (increased non-linearity, distortion, obvious degradation in sound quality).
Subjectively, the Crown sounds better than my old 165W@8ohm stereo AVR.... but the difference is marginal and might even be non-existant (could I tell the difference in double blind?, maybe not!)
The Crown does sound vastly superior to my current 100W AVR - but I think that is due to its small power supply, and resulting misbehaviour into my speakers - when used as a pre driving the Crown, everything sounds as it should (Great!).
Given your polks are 8ohm nominal.... and relatively high efficiency... I doubt there would be an audible difference between the two amps.
I should mention that the Crown XLS series (1st and 2nd gen) are often available used in the DJ/Band/PA marketplaces... I purchase my XLS2500's for US$250 each (I have 2).
Personally I would look around for used Crown bargains...
Also the Crowns are designed for the rough wear and tear of a pro amp (think crash and bash!!)... which in a home environment tends to imply very long trouble free lifetime!! (I have had mine for over 10 years now)