Hang the ceiling using an acoustic ceiling to avoid noise.

Well, I mean the "old" Naim NAC / NAP amplifiers (certainly not current WLAN cubes - WTF are they even making now?)

I left the scene back when harman/kardon (even before Mercedes) entered the mass market and began to focus on the Gucci-Rolex-fake clientele. At that time, no one suspected that DAT would one day follow the same path as Betamax before it ;-)

we are currently veryyyy off-topic and I hope the OP understands, maybe is even interested in continuing to follow this? Still, this should now be my last off-topic contribution here ;)

Well, THAT was not an option for me back then. It just had no "charm," I had a very charming Revox tape recorder for that (just watching the device work was worth every penny ...) and considered (but did not buy) using a video recorder for hi-fi purposes. Not uncommon back then ... Harman/Kardon was just for the glitter/blicky crowd ( the designation is even better for that), but back then it could also score points with real wood side panels ;-)

back on topic, our multipurpose room, 55m2, open upwards under the saddle roof, 25-degree roof pitch, almost 5m height, plastered, drywall panels, as an empty room hall, furnished with carpet and furniture with slight reverberation, no acoustic measures. Moved in with 5 Brüllwürfel and bass box from Bose and Yamaha receiver, the result so-so. Decision was discussion with the finance minister and must be redone. Consultation with high-end colleagues and rejection of extremes. Our solution 4.0 system, Nuvero140 and 60 (bass range 4x directly from the speakers, no insertion of a bass box audible) in the 4 room corners. Pioneer receiver 901 with measurement system, success surround sound in the multipurpose living room dining kitchen with TV, radio and records. I think with a flat ceiling we would have more problems with reverberation

Multi-family wooden houses with wooden ceilings can also meet the soundproofing requirements. Essential under the ceiling are the spring rails. Soundproofing over flexible bending board GK 12.5mm. Wooden beams min. 220mm with 100mm cavity insulation.

on topic:

our "all-room" (I don't like the term) about 80 sqm floor area on 2 levels, asymmetrical gable roof, height up to just under 7m, Ligno Trend ceilings, neither echo nor "damping pressure".

I can only warmly recommend the stuff.

off topic:

as an exhibitor among others with Dali, Chario, Meracus, Clearaudio, German Physics, Primare... (sales representative)
as a dealer among others Gryphon, Dali, Chario, Aragon, Papworth, Moth, NAD, Valvet, Audiomat, Brinkmann, Acoustic Linear, German Physics, HMS, Straightwire, Kimber... stuff like that (own shop with a spectacular crash landing after not even 2 years - I completely misjudged myself and was totally overconfident - paid and learned, maybe that is why I often have the attitude "it's just money," because time matters and comes, unlike money.)

DAT - was studio standard for quite a long time and thus quite successful. I even had it in the car. Today the systems in the cars are unmodified, only in the motorhome did I buy again.