Wooden floors full range big speakers that go low, bad combo for turntables on anything that sits on a wooden floor.
I had similar back in my Linn LP12 days, very frustrating.
The answer for me, after trying everything, was to suspend the turntable by 4 thin chains or you could use fishing lines from the ceiling, that stopped all mechanical feedback coming up from the floor and it sounded very tight in the bass.
Cheers George