Ah, I re-read your original post. It looks like you have a very large rectangle room (open room) that contains both kitchen and living room. It is still considered a single room and will have bass "room nodes":
https://amcoustics.com/tools/amroc?l=45&w=17&h=10&ft=true&r60=0.6
This means that certain bass frequencies are going to be cancelled out at your listening position. In addition, bass will tend to build up and sound louder in the back of the room (where you are sitting at the kitchen island).
Building a wall in between is not likely to improve things at all, unless you can build a "permanent wall". Your Krell FPB400CX is a very high power amp and you do not need to replace it.
I would start stacking up bass traps in the corners. Look at GIK Monster Bass Trap with FlexRange Limter (I know --- I love to recommend these things). Or maybe a GIK Soffit trap with scatter plate built in. You seem to have a lot of very low frequency room nodes (33hz, 37hz, 49.9hz, 56hz, 62hz, 66hz). The Monster Bass Trap with Flexrange will not be as effective for stuff under 70hz (but it’s still better than nothing).
I always hesitate to recommend full broadband bass traps (such as Soffit without scatter plate or Monster without Flexrange Limitor) because they tend to suck out too many high frequencies.