The 220 volt mains power supply is often contaminated by noise carried over the actual power cables itself. While a simple Stage 1 filter will reduce the noise, if you want to attack the problem head-on you will have to get a Stage 2 filter.
These filters are custom quoted and built and the price varies by design. Have a look at the photo of the Extreme version!
Much of the knowledge behind this device comes from the late Steve Hunt G3TXQ, whose deep insights will be sorely missed.
Why don’t you watch his video on YouTube Steve Clean Up Your Shack