Those or similar have been discussed here years ago. IIRC the ones having them liked them for added immersion. Some people have massive subwoofers below their seat for the same reason, some guy even built a simpit wit built-in bass speakers in the seat and the backrest. And - can it really be that long? - a couple of decades ago Pioneer had such rumblers installed inside car seats instead of a subwoofer. So the idea isn't new or revolutionary, more like there really aren't enough enthusiasts to buy those things in such masses that their prices would drop to a level affordable for the average Joe - or rather acceptable to his wife
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As you may well know, those are basically speakers without a diaphragm. Instead there's a pole beating the bottom of your chair. Such can even be done out of old speakers!
