Idle noise is usually very low, but the experience depends on mode. One reviewer heard virtually no hiss or hum, while another noticed audible hiss in ANC or transparency with...
Pros: Codec support, aptX
Cons: Wear detection auto-pause, Wind noise handling
A strange underwater-like static can be audible when no music is playing. It disappears once playback starts, but the idle-state noise is still an unwanted flaw.
Pros: Maximum volume clarity, Microphone quality for calls
Cons: Idle static noise, Instrument separation