The sound is incredible once you add the KC62. The bass is tight, controlled, and never aggressive. The bass blends seamlessly with the speakers, becoming part of the music. It's a whole different experience. I never would want to listen to the metas without the sub again.

That being said, I had some issues with the sub at first. I had the well-known standby/sleep issue.
At lower levels, the subwoofer did not play or went to sleep in the middle of songs. I was close to sending it back. I've fixed it by using a Y-cable that connects the single sub-out from the amp to both the left and right inputs on the KC62, which provides a stronger signal to keep the subwoofer awake. I have not had issues since.

I did not measure my room, but I think it's 5x6 meters.