I grabbed two of these to correct an issue with a custom audio network between two computers, an office phone, a cell phone, and one headset with microphone.
Understandably, this generated a lot of hum, hiss, and clicking on its own, especially when the cell was plugged into the computer to charge...
With both phone outputs run through these, there is not a single click or hum left in the sound, and the stereo separation has actually improved.
In short, these have done the seemingly impossible - highly recommended!