Horning Eufrodites - help needed with boomy bass

Tom is right,
I have done much more extensive structural changes in my room in order to tame room bass modes. It is a difficult decision, but by looking at it, shouldn't be that difficult to implement technically- and, you will thank yourself later.
Without some serious re-building you will be "doomed", as far, as the bass goes

Sorry the boards-in-the-port didn't help.

Equalization or a solid state amp are probably your least room-intrusive possibilities at this point. And nothing wrong with room treatment.

Unfortunately I don't have any more inexpensive suggestions.

It is possible that a couple of small, cheap subwoofers, placed one behind each of your speakers and operating out-of-phase, would introduce enough cancellation to smooth things out.

Duke

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.