What am I to do about

Don't get fixated on the "metal domes sound harsh" school of thought. I think that the amplification you mention could be the source of the perceived harshness. The room would be my first choice as the culprit though, but since you said you tried three rooms,I am suggesting the amplification. Could it be all three rooms were bad? Quite possibly. BTW bass now generally sounds tighter on newer designed speakers. Maybe you just have gotten used to more bloat and the tighter more punchy bass does not soften the overall sound to your liking. Just a thought.

It is hard to know how to comment on the harsh sound based on the small amount of info given. It is my contention that the biggest problem in most systems is the room. Pbb might be right (there's a first time for everything!) because nothing stands out in your system as being a real piece of @#$%.

Improvements could be made everywhere, but for the cost of one moderately priced piece of gear you could get the room fixed. Then everything you buy down the road will sound that much better.

When you stand in your room and talk, how does it sound? Is there a lot of echo present, or does your voice sound dull and muted? What ever characteristics or colorations you notice in your voice are the same things that are happening to the music.

If any of these issues are noticeable, address them and your system will sound better too.

The Paradigm 100v2's never sounded harsh to me and I've heard them with several different amps. Mine are hooked up to a Sunfire, which tends to be a bit warm, but I've also heard them with Brystons, which tend to sound a bit cold. Jdombrow, Pbb and Nrchy made fine recommendations and suggestions. Has anything other than the Polks changed in the last five years? Same room? Same furniture, carpets, etc? Same other equipment (even if the latter is the case, synergy is everything)?

1/Make sure you do not have any Power cords touching your interconnects or speaker cable.

2/Make sure the binding posts on the back of your speakers are not loose.

Cford what types of music do you listen to and who are the record labels ? I see plenty of folks blame their equipment for just bad recordings.Unfortuntely some recordings are just not made well.It maybe time to bring out the tone controls.The more revealing your system becomes the more you will notice it.You could do like some and buy a tuby preamp and smooth things over. A preamp with good tone controls would probably do the trick.This way you could adjust it to your liking.

Also whats the toe in on your speakers? You may want to toe them out a bit.I see people say the room is important..which is true. But what about the recordings.The recordings are also important. Some of them you just have to take them how they are or toss them ! LOL

Maybe one of these days all record labels will be on track like Chesky,Blue Note,Telarc,Rounder and Verve.
Until then I will continue to be very selective of the recordings I buy.I listen to mass market in the car!

Good Luck!