Many audiophiles fret that the power to their equipment is noisy and distorted. The thinking is that if the power in is of poor quality, the music produced by the equipment is of poor quality too. To remedy this, the ‘phile might buy an expensive power conditioner or regenerator that is essentially a special power supply that modifies the mains power (Note: “mains” is British for the stuff coming out of the outlets in America).
Are these devices helpful?
Mostly no. Most modern DACs and amplifiers use very well-regulated linear or switching power supplies to convert AC into DC power. Moreover, some of the well-known power conditioners don’t really live up to their claimed benefits, introducing more noise into the regenerated power rather than less. Audio Science Review has some great analysis of some of these devices.
There may be situations where they are helpful, however, like when utility power is highly flawed with drooping voltages or brownouts. Often, in these circumstances, a battery backup system or uninterruptible power supply (UPS) does the trick and without the extra expense that audio equipment manufacturers add to their special devices.
