AudioQuest XLR Output Noise-Stopper (Male) Output Caps - Set of 2In a world immersed in RF EMI interference we all need the sound of silence Nothing makes an audio video system more irritable than RF interference the bane of dynamics and clarity. To reduce the amount of RF interference entering your system we recommend capping all unused RCA and XLR inputs. Youll be pleasantly rewarded with a blacker background, deeper sound stage, and a richer more satisfying overall experience.