Hi Hector
The floor is a 40mm screed with underfloor heating over 100mm Celotex and block and beam, it will have an LVT Karndean flooring added soon. I wanted the walls in soldi plaster but we ended up with dot and dab which I know can resonate. The ceiling is insulated plasterboard which is unlikely to resonate.

We will have a sofa and chairs in the way of soft furnishing. Windows will have roller blinds. One end of the room is all glass so its far from perfect as a listening room.

DSP5200SL, 218, with Sonos. Rest of home Loxone multi room audio with Monitor Audio speakers