Audiophilepure

https://www.stereophile.com/content/gramophone-dreams-49-kef-kc62-subwoofer

I will spare you the details of my experiments. Suffice it to say I preferred the LS50s running through the KC62’s high-pass filter set to 40Hz. Relative to baseline, response was now +2dB at 40Hz, –5dB at 31Hz, and down just 20dB at 20Hz! Midrange clarity improved even more. But what impressed me most was how now, with the LS50s running through the high-pass filter, subtle changes in rhythm and tempo became more obvious. After getting nice measurements, I put on a variety of piano recordings and used them to tweak the woofer’s level. I turned it down until the keyboard’s upper, mid, and lower registers connected seamlessly. With the KC62 sub, the LS50s sounded more relaxed, tonally even, and natural.