Weak link

1st, document what you are actually receiving at your ears, seated position

cd with test tones

Here’s one on eBay

Amazing Bytes CD with 29 1/3 octave Test Tones

Sound Pressure Meter, with bottom threaded hole for tripod mount

Meter on tripod, at seated ear height, at listening position.

Meter doesn’t need to be that precisely calibrated, you will get more or less answers relative to adjacent frequencies.

Make enlarged copies of the insert with test tone list so you can write down the results

Go forth informed

IF you have any tone controls, you can measure the results, and you can make adjustments for your personal taste, perhaps you have age related diminished hearing of high frequencies.

also, great tools to accurately measure the effect of alternate placement/toe-in.

room treatments are always good, but i agree with the get-a-sub--your kefs are great but i believe only go down to 35 or so.

Sorry I  didn't list it, but I have a single REL S510 subwoofer.

Room treatments.  Hands down this will be the best bang for the buck.  Why spend money on better/more equipment when it will be conflicting with sub-optimal room acoustics????  Good luck and cheers 

If this list of equiptment doesn't sound fantastic then there's something wrong with either the room or the placement/location/toe in/ triangle size of the speakers and proximity to the listening position. You really don't need any more or better electronic gear. IMO.