I'm using mineral wool-coated dry screed floor panels in my drum room.
https://www.aquapanel.com/products-s...t-board-floor/
They are quickly and easily placed, don't take away a lot of room height (3 cm), can quickly be walked on after install and provide a firm and sound de-coupling base. The resulting floor surface has gaps at all borders, never touching the drywall room-in-a-room wall construction to prevent vibrations passing from the booths floor into the drywall. I've put laminate on top incl. another layer of footstep sound insulation. The acoustic and de-coupling results are very good.
A very good source of information on the topic is John Sayers' website with its studio design and construction forum:
http://www.johnlsayers.com/
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