Connected from a desktop PC to a sound console, for recording from turntables and cassette players, and for playing music from the PC to the console through a final amplifier. The PC produced noise and interference when connected to the console, and you could hear the mouse, fans, etc. The problem is mostly due to the power supply of the desktop computer, which leaks noise due to aging or low quality capacitors, etc. The filter reduced the noise by 90% to 95%, BUT it is probably of low construction quality in terms of sound quality, as it can distort the sound quality when bass or volume is increased, and also because it operates in a way that cuts out "bad" frequencies of noise, low frequencies, etc. The sound/music produces more mid-range frequencies and loses in volume and detail. It brings a somewhat tinny sound, as if you were listening to a transistor radio, and it reduces the volume by 40%. You gain in noise problem, BUT you lose in sound quality. If you want to save 150 euros + for a new and quality power supply, with 10 euros you can solve this problem.