I don’t know Lyngdorf, but a good sub with a well built cabinet should not be vibrating. A large part of the cost of a good sub is an acoustically inert cabinet in fact. So if you have a high quality sub, the vibrations didn’t ought to be a major issue.
Placement is the main problem for me with this. Your cabinet is very unlikely to go where is best for the sub. You can fix that with two subs and a miniDSP but now you are spending a lot more.
This is how I have my multi use room set up: two subs in basically OK locations but not ideal. They are dialed-in using MSO and a miniDSP to create a combined response that’s close to perfect. The subs themselves are hidden behind acoustic fabric over a frame, and covered by custom table tops. The table tops make no discernable difference to the sound and even the REW measurements show practically no effect.
You nailed it…