I recently switched to Openelec from Win7 with KODI, and changed a few pieces of hardware so can’t say for certain if hardware or software causing the issues.
Basically, from the main screen of KODI I have a high pitched hiss. I still have it if streaming (most of the time). If I play a video file, it goes away, even if I click pause, the sound is gone.
OpenElec/Kodi is running off a 32GB SSD drive, which is new (use to be a 250GB HDD) and I also swapped out the GTX650TI card for a fanless GeForce (forgot the model). Also replaced the CPU fan for something quieter. Wanted a quiet HTPC, but after switching to a new case, it was pretty loud. Sound carried a lot more.
So, not sure if the software making the hiss? I don’t think the GPU/HDMI else why would I get hiss from streaming not from stored files?
I do have 2x3TB HDDs with TV/Movies on them, and it’s when I play from there that I no longer have the hiss.
Could the sound be from the cheap SSD drive? fans? software?