I received my second HTC One (Black) on the 19th of April and unfortunately it has exactly the same problem as the first, it is from a much more recent batch as well (April).
I get a loud hissing sound while watching youtube videos and playing games, while watching the new superman trailer on youtube you can hear the hissing from across the room which ruins the phone for me.
I never actually got to test call quality on my first HTC One since I hadn't been sent my new sim card but I have tested it on my current One and I get hissing when ever someone talks / there is noise.
I notice their are a few people saying audio is perfect and they can't hear any hissing a tall but they seem to be in the minority. Unfortunately my current HTC One has multiple dead pixels and along with the audio problems I think I'm about ready to give up which is a shame because this is an amazing phone.
-Aziki
I just tested that Superman Trailer with my HTC One and compared it to my Samsung Galaxy Nexus.
I do hear the hissing but only when Beats is turned on. When I turn Beats off it sound exactly the same my Galaxy Nexus.
Also with Beats turned on, play my own audio files there is no hissing.
This leads me to two theories. One, its a software issue. Two, the issue is not the phone but the audio quality of the file itself. From what I've heard Beats seems to amplify everything in the sound itself, thus possibly amplifying the noise that was there already but we couldn't hear it.
Can anyone confirm this with me with the Superman trailer?