Siblings in Polk Audio's Monitor XT series, so they share a family sound. It comes down to size, output and price.
| Area | Better | Why |
|---|
| Bass | B | Polk XT60 digs deeper - 38Hz against 94Hz. |
| Amplifier needs | A | Polk Audio Monitor XT90 is more sensitive (89dB vs 86dB), so it goes louder on the same amplifier. |
| Size | depends | Polk Audio Monitor XT90 is easier to place; Polk XT60 is bigger, which usually goes with fuller bass. Your room decides. |
| Type | depends | A Passive Surround against a Passive Floor-standing - a different job rather than a better one. |
| Cabinet | depends | Ported vs Passive Radiator. |
| Expandability | B | Polk XT60: Atmos drivers. |
| Price | A | Polk Audio Monitor XT90 is cheaper - $119 against $498, about 76% less; arguably a different class. |
A Polk Audio Monitor XT90 B Polk XT60
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?
Polk XT60 is ahead, but only on 1 of the measured areas, and it costs about 4.2x the price. That is a lot of money for a narrow margin on paper - Polk Audio Monitor XT90 looks like the sensible buy unless something else about the Polk XT60 appeals to you. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 94Hz anyway, which makes the cheaper Polk Audio Monitor XT90 much easier to justify. In a large or open-plan room, Polk XT60 has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, Polk Audio Monitor XT90 is the easier speaker to get right.
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.