@kvpower getting those KEFs is a great move. They are tiny and easy to place yet go down to an astonishing 14 Hz, I think.
(I am myself a KC92 owner. A fantastic sub, but a tad larger than the KC62.)
And as other people have mentioned it is not only about adding the lowest frequencies but to fill out the entire bass range throughout the room.
Just make sure to don’t make the common mistake and place them next to each main speaker but diagonally in the room as much as you’re able, for that very reason of avoiding bass nulls and peaks you inevitably will get if the bass only emanates from the main speakers location.