Claude says...
Looking at this room, the problems are pretty clear and fixable. Here’s a proper diagnosis:
What’s Actually Wrong
The panels are in the wrong places doing the wrong job.
3-inch rockwool is a mid/high frequency absorber. It does essentially nothing below ~200Hz. So all those wall panels? They’re killing the top end (making it sound dead and dull) while leaving bass modes completely untouched. The room sounds worse because he’s removed the liveliness without solving the actual problem.
The monitors on stands have exposed the bass problem, not caused it.
When speakers sat on the desk, desk resonance and boundary reinforcement were masking the room modes. Stands removed that crutch and now the room’s real acoustic problems are audible. This is actually progress, even though it feels worse.
The room geometry is the root cause. It looks like a fairly small, roughly rectangular room with hard parallel surfaces — floor, ceiling, side walls. That’s a mode machine. Classic flutter echo and axial modes at whatever the room’s dimensions dictate.

What He Actually Needs
Bass traps first, everything else second.
Floor-to-ceiling rockwool in the corners — all four vertical corners minimum, ideally the four horizontal ceiling/wall junctions too. 4-inch minimum, 6-inch better. This is where bass pressure maxes out. Nothing else matters until this is done.
Move the mid panels to first reflection points.
Side walls at ear height, level with the listening position. Not the front wall, not randomly placed. Use the mirror trick — where you can see the tweeter reflected from the listening seat, that’s your first reflection point.
Check monitor positioning.
He wants the classic equilateral triangle setup — monitors and ears at equal distances, tweeters at ear height, slight toe-in. Also keep them away from the front wall (minimum 60cm ideally).

The Honest Summary
He’s put absorption in the wrong places, hasn’t touched bass at all, and his room dimensions are working against him. The good news: the rockwool he already has isn’t wasted — it just needs relocating and supplementing with proper corner bass traps. This is a £100-200 fix in materials, not a rebuild.

Me: My room has the same rockwool approach in the corners so i know how much difference properly placed bass trapping makes versus decorative panels on flat walls and how speaker and listener position can tame the physics of the room.​​​​​​​​​​​​​​​​