I've owned/reviewed more power line conditioners than I'd like.

About the only thing I can say for sure is that they all work to a degree, but whether you get the optimum benefit will vary on your location and what powerline anomalies, RFI, EMI, low/high voltages, etc., may exist in your area and which unit you are using.

Then there is budget. Most of the inexpensive PLC don't offer much more than surge protection. The pricier units really offer significant audio/video improvements.