Walk around in the room and determine if some satisfactory bass output is present at a location other than your listening location. Move speakers a bit closer to the front wall and walk around some more.
If you are sitting on top of modal nulls, you might start to wonder where all the bass went. If you can’t move your listening position, correct positioning of subs and sub phase adjustment would be the way to address such nulls.
Do a battery tap on each speaker and see if the woofers are moving in the same direction. (check if some Italian guy wired something wrong when he was coming out of riposo)
etc
Did you try a different amp? Some half broken amps can make all the bass disappear, depending on the issue. Take it to some local tech (if you are not set up to bench stuff at home) and check it out. Here’s an example
https://www.youtube.com/watch?v=M8vhVTQ1cLo
On a positive note, those KEFs are nice subs.
It could also be that your Amati is a slightly bass flaccid speaker overall, with emphasis on looks and mids "sweetness", tailored for Diana Krall, not MC Ren.