Different kinds of product: one is active with its amplifier built in, the other passive and needs one. Judge them on how you want to own the system, not just the specs.
| Area | Better | Why |
|---|
| Bass | B | Polk ES20 digs deeper - 41Hz against 55Hz. |
| What you buy | depends | Klipsch R50 PM is a complete system - just add a source. Polk ES20 also needs an amplifier: more money and another box, but you choose it. |
| Connections | depends | With Polk ES20 that all comes from the amplifier you pair it with. |
| Upgrade path | depends | Polk ES20 can be re-amped later and outlive several amplifiers; Klipsch R50 PM ages as one unit. |
| Size | depends | Klipsch R50 PM is easier to place; Polk ES20 is bigger, which usually goes with fuller bass. Your room decides. |
| Price | B | Polk ES20 is cheaper - $399 against $450, about 11% less. Speakers only - an amplifier narrows that gap. |
A Klipsch R50 PM B Polk ES20
depends neither is better in the abstract - it turns on your room, your system or how you will use them. Only specs published for both speakers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
Klipsch R50 PM suits you if you want one box, ready to play, with nothing else to buy. Polk ES20 suits you if you already have an amplifier, want to choose the electronics, or expect to upgrade in stages. Neither is the better speaker in the abstract. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 55Hz anyway, so judge these on the other rows instead.
And remember what a spec sheet cannot show: how each looks in your room and whether the finish suits it, what dealer support and warranty are like where you live, and how they actually sound to you. If you can hear them first - ideally with your own music - that will tell you more than any number above.