At the heart of every high-end audio system is ground. It's where our audio signals, from the tiniest moving coil cartridge output to the largest output from our preamps and sources all reference to. The cleanliness of that ground has a major impact on both sound quality and noise levels. In a perfect world, our audiophile-grade systems would benefit from a dedicated ground, one that only the stereo system is connected to. But, most of us don't live in perfect worlds. More often than not, our home audio systems commingle with connections to the outside world and this can be problematic. Noise and ground contamination enter our homes and dirty our grounds through CATV connections with the cable company. If your audio system has any connection to your AV system, or a cable internet modem, then you need PS Audio's HumZero.