Horning Eufrodites - help needed with boomy bass

Must be sleepy time in Paris..

I used to run Zu Definitions 2 spkrs with xoverless full range drivers and 4 x 10" rear firing woofers per spkr, ie many similarities to your Hornings. Always found bass had a tendency to boom and overpower the room. My solution which was c80% effective? Installing a Spatial Computer Black hole anti-bass wave generator. This is in effect a one cubic foot subwoofer sited behind/alongside the listener next to a wall, with integral mic which samples the bass put out by the main spkrs; via dsp, it puts out a cancelling wave of bass, so dealing with standing waves and bass nodes.
Bass hash/boom was much improved, with subsequent improvement in intelligibility, transparency and dynamics.
At $1300 with a full money back guarantee if not happy, you can't go wrong. Clayton Shaw who runs the company is one of the good guys in audio.

all, as you can see, my system is in the middle of our, a family of six, living room hence I'm trying to avoid adding all types of electronics all around to compensate for acoustic issues.

it's also ideally all day long that music is playing in this room hence it has to sound at least decent, i.e. as in no boomy, all around as opposed to only sound good in the sweet spot.

it's also important to note the fact that it's beyond my capacity to now go argue with a French real estate agency who runs the building we live in, about if I can or can not take down a piece of a wall that did survive two World Wars and other events since its construction in 1895.

the good news are, that being definitely convinced, as some folks have suggested, that the problem comes from the structure of the left side of the room, I started by simply dropping a carpet over the white cupboard under the CDs rack and, without celebrating too much yet, I think it's making a not so marginal difference, to the positive side of things.

so now deep breath, focus, no panic (as other folks have so truly suggested).
I'm going to continue going down that route, treating the "boom boom corner" on the left.

cross fingers, sit still and wait for breaking news.

and if you have more suggestions, please.

Amuseb

The cabinet under your cd's has vents which from this side
of the ocean makes me think the doors are metal and
something mechanical is behind them. If you could open the
doors or remove them that may help. If the cabinet needed to
stay the way it is now and it could be emptied.. filling
with stone or creek rock would help. You need to port the
cabinet so air will pass thru like an intake and exhaust of
a car. The stone will act as natural diffuser and not as a
damper like foam or fiberglass. You should also put stone
underneath the cabinet on the floor. You could cover these
areas that contain the stone with grill cloth. The cd
cabinet above... could have a full width door that fits
flush against your music collection. From the front, the
door would be hinged on the right side with the door handle
on the left side. When you are playing music you could open
the door so it's angle will steer the bass around and in
front of the wall with the 90 degree angle. This will bring
the bass pressure more to the center of the room and reduce
standing wave resonance in the area around the niche. Tom

Amuseb, are you really sure you can't site a diminutive 12"x12"x12" sub behind you, with one power cable? You could even put a vase of flowers on top to obscure it (max WAF!).
It REALLY solved my boomy bass issues, and maybe more than other contributors here, my prev spkrs are probably as close to yours, and hence experience similar, so I know where you're coming from more than most.
Clayton offers full money back if it doesn't solve your needs. Worth a try, surely?