[gentoo-user] Advice Needed: Conexant HD-Audio noisy audio

[Ignas Anikevicius <anikevicius@gmail.com>]

Dear all,

It's been quite a while since I noticed this annoying behaviour, but I
could not find any information what might cause this. So the problem is
that at lower volumes my HD-Audio with Conexant becomes very noisy and
this is regardless of the sound system or speakers/headphones I use.

The noise can be described, as high pitched, sandy texture noise
heard during more expressive parts of the music or speech.

I experience this on two Thinkpads (x200s and x200) and it very evident
when I connected external speakers, they produced a lot of this noise,
or maybe I just could hear it better, because of the frequency response
of the speakers.

Does anybody have some similar issues?

My current audio setup:

    * PulseAudio (but the problem is experienced with ALSA as well)
    * MPD for music playing
    * Conexant and other related modules compiled in, power-saving
      features enabled.

What I have tried to eliminate the noise:

    * Various levels of Master,PCM,Headphone channels via Alsamixer
    * Increase the sample rate in MPD settings.

The noise can be clearly head when I Have the following setting on my
Alsamixer:

    * Master ~50
    * PCM 100
    * Headphone 100

Does anybody has any thoughts on why am I experiencing this?

Thanks a lot,
Ignas A.