"The turntable sits on an antique wrought iron table with glass top. It sits about 5 feet from the speakers. "
I saw this post from you after having submitted my last post. At least by description, your set-up sounds like a set-up for woofer pumping. Not only is it possible that your tt is too close to the speakers, but glass is not an optimal shelf material for a turntable, suspension or no suspension. Glass is highly susceptible to environmental influences especially including airborne energy from the speakers.
I saw this post from you after having submitted my last post. At least by description, your set-up sounds like a set-up for woofer pumping. Not only is it possible that your tt is too close to the speakers, but glass is not an optimal shelf material for a turntable, suspension or no suspension. Glass is highly susceptible to environmental influences especially including airborne energy from the speakers.