Enclosed speakers ARE instruments. They are enclosures used to channel sound like an oboe vs a saxophone.
Sorry, but that's just not true. The only thing reproducing sound should be the electrical speaker driver and the mechanical port. Other than that,the speaker box is NOT designed to add anything or resonate in any way and should be as acousticalley invisable as possible.
I bet those concrete, rounded speakers sound amazing! They also measure really well.

