Interference-free Sound

When listening to your favourite CD, any audiophile will at some occasion realise that the CD concerned used to sound better during the previous listening session. Or perhaps just the other way around. The cause for this difference in quality cannot be directly traced to one of the carefully assembled chain of audio components and saddles the listener with a feeling of uneasiness. To exclude all technical causes we need a decent mains filter, which at the least ensures that nothing can be blamed on the very beginning of the audio chain, the power supply.