Review on 🔇 Pyramid NS20: Advanced 15A RCA Noise Suppressor for Clean Audio Signals & Noise Elimination - Built-in Isolation Transformer, Ideal for Amplifiers & EQs, Easy Installation via RCA Jacks & Unique Noise Detection Circuit by Marquel Floyd

Good job removing engine noise. Unfortunately, 80% of the desired low-frequency tones have also been removed. In other words, all bass is gone. May be suitable for small speakers with noise problems. Definitely not a high quality noise canceller. I ended up returning this and installed a noise filter on the incoming power cord and found a direct ground to the case to eliminate the noise.