This might just be something stupid, but it had me stumped for a while. I'm fairly new to Knoppmyth, but have been a Linux user for a long time. I installed Knoppmyth on well-supported hardware (7NIF2, Sempron 2200, etc.), expecting great results. Everything worked as expected, except the sound quality was bad (buzzing or humming in the background).

The solution was as simple as increasing the sampling rate on the audio portion of the software encoder. The intel8x0 driver will always resample audio to 48khz on output, so the default encoding rate of 32khz was causing the strange hum in the audio. Changed the encoder to 48khz, and my audio is as clear as can be.

Hope this helps someone out there with the same intel8x0 issue.

Enjoy!