These actually worked!
Crutchfield Customer Review (What's this?)
These actually worked! I hear lower levels of quiescent noise from my Anthem preamplifier and amplifier after implementing the "AudioQuest RCA Noise-Stopper Caps" on the dozen RCA inputs.
Pros: The pro, they work. You will experience much lower levels of quiescent noise from your preamplifier and amplifier after implementing on all RCA inputs.
Cons: The con, all AudioQuest products prices are high for some family budgets. However, when you spend thousands of dollars on preamplifier and amplifier, the cost is not bad.