To prevent your subwoofer from transmitting unwanted rumble through the floor, you can use isolation feet such as the new Stack Audio Auva SW.
According to the manufacturer, the Stack Audio Auva SW isolators are designed to improve the accuracy of your subwoofer. A nice “bonus” is that your downstairs neighbours will experience less low-frequency disturbance. The feet-cum-isolators are engineered to better control low-frequency energy and reduce unwanted vibrations. They are specifically tailored for use with subwoofers.
Each isolator uses a special damping core filled with fine particulate material, combined with a custom silicone absorber. Installation is simple: you can place them directly under the subwoofer with no further modifications required. Adapters are also available for subs with screw-in feet. The dimensions of the isolators are 35.4 mm in height and 50 mm in diameter, and each one weighs 120 grams.
A set of four Stack Audio Auva SW isolators costs €379.22. Several CSA (custom silicone absorber) options are available to ensure proper support for different subwoofer weights.