Eliminate Noise from Your System with AudioQuest Noise-Stopper XLR Caps Everyone knows that noise and distortion are bad for audio reproduction, destroying precious detail and smearing resolution. Your open XLR inputs are channeling RFI and EMI noise right into the heart of your components. Cover all the unused XLR inputs in your system with the AudioQuest RCA caps and keep this distortion from getting into your components. AudioQuests caps slide right over unused XLR jacks and will provide both sonic and environmental protection.