Oh Boy, did we ever fight that problem back in the days before CD's! I'm not telling my age but my first "high end" turntable was a Garrard model 50 (yuck!). I think Steven has touched on your problem however, I suspect that rather than an ifrasonic situation you may have a subsonic problem. Please believe that your speakers don't like that high excursion and neither does your amplifier. Although probably not totally accurate I offer the following analogy: Think of your turntable, arm and cartridge combination as a microphone. If you walk across a hardwood floor and the vibrations of your footsteps travel to your rack and then the shelf and then the turntable, the turntable (microphone) will pick this up and send it through the signal path along with the music. Bass information from your speakers will do it too. Big time! This can come from the vinyl itself due to warps etc. Subsonic filters will obviously filter most of that out but the problem is still there and still affecting the overall sound of your turntable system. Also, depending on your speakers, these filters can remove some of the lower bass information that you want to hear. Isolation is the answer. There are some good isolation platforms available today that we didn't have years ago. Back then, a friend had a Fried Model H speaker system with a transmission line subwoofer that was to kill for. We finally ended up with the speakers being the only component in his listening room. The rest of his components were in another room and the base of his turntable was packed with duct-seal. Problem solved. Isolate that table by whatever means necessary be it a platform, cones, etc. As far as subsonics from the vinyl itself I would suggest a record clamp. At least that will help with warps and keep the record pressed to the mat. Good luck and happy listening.