I do not notice any hiss with K3 with any headphones. I noticed hiss with other radios. Ignacy, NO9E -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-background-hiss-noisy-K3-update-tp7608490p7608498.html Sent from the Elecraft mailing list archive at Nabble.com.