@gdaddy1 you described a concert piano on stage without a cage and lid or a cello without a bout and sound holes!
Enclosed speakers ARE instruments. They are enclosures used to channel sound like an oboe vs a saxophone.
I don’t believe ’unwanted’ resonance is the same as zero resonance. How popular are concrete or aluminum piano and cello? Wood has a warm sound people like.
Recordings are not perfect. You still need to restore some of what’s lost, like the sound and resonances of wood instruments. I’ll save my final judgement when I hear it, but I can’t imagine an echo box concrete speaker to reproduce the warmth and resonance of wood instruments.
Maybe an open baffle or magnapan is more your thing. I would still want the sound of wood, just not cheap thin wood.

