Question about Samsung HW-Q990D

22cm is the housing + 1cm is the loudspeaker still on the outside. A total of 23cm, but you need some additional space on the right-hand side, as this is where the speaker is, so that the sound can spread out. See last picture. 24-25cm is theoretically feasible, but whether it still sounds good is another question. Personally, I wouldn't go below 33cm.

Specifications are correct: Width 22cm, height and depth 41cm each