alsa-ucm: Turn down the headphones volume to avoid distortion

The maximum values used previously are very loud compared to other devices and cause a lot of distortion. This sets the main volume to 0dB and disables additional gain, resulting in still very loud but now quite reasonable maximum volume.

Fixes #31 (closed)

changed the description

changed the description

The distortion is a problem we should look at but for my taste the new values are way too low to be useful with ambient noise and even more important if you want music to actually rock.

(Edit: If others think otherwise please merge)

@guido.gunther It's still very loud for me, comparable to what other devices output on max volume - so loud that it would be painful to listen to it this way for prolonged time.

On which batch you're testing it? On Birch I have to push the plug in pretty hard, otherwise it doesn't make full contact and it's not as loud (although the bundled headphones go fully in pretty easily - depends on the size of the plug). No such issue on Dogwood.

(basically, if you hear the audio on both channels in your headphone then you're driving both speakers with single signal for one speaker)

that's birch (which doesn't care how hard i press the HP on my device but i've read that this changes things for some people). If that changed for dw and it's louder it's likely be o.k. - somebody with a device where that is working might want to merge that then (e.g. @martin.kepplinger)

With the plug in correct contact with all the pins you should hear audio only in the left channel, with the right one staying silent. Is that the case for you?

got a dogwood with functional headphone jack and can confirm it's very loud with the current values - since nobody else seems to bother lets merge this. thanks.

merged