Bad quality sound on MoodeAudio 6.x

[Tim Curtis]

Audio devices that include an on-chip or on-board Hardware volume controller expose an ALSA layer volume control via their device driver. This is separate from the Software volume control that is part of the Player application which in this case is MPD.

MPD volume control (the moOde knob) can be configured in 3 ways
1. Software - Use MPD internal Software volume control
2. Hardware -  Use the devices Hardware volume controller if one exists. This is the ALSA layer volume control.
3. Disabled - Output 100% (0dB) volume which bypasses internal Software volume control

ALSA layer volume is configured as follows depending on the MPD volume control setting
1. Software or Disabled - ALSA volume set to 100 (0dB) so the overall volume when Software = 100 is 0dB
2. Hardware - MPD volume setting controls ALSA volume (the devices Hardware volume controller)

I ran a quick test with MPD Software volume set to 100 and Max ALSA volume set to 85. Alsamixer showed level = 48, -19dB gain, amixer showed level = 85%, -19dB gain. Note that alsamixer and amixer report the same gain but alsamixer uses its weird cubic scale to report the level while amixer uses a straight percent scale.

Code:

pi@rp3:~ $ amixer
Simple mixer control 'Master',0
 Capabilities: pvolume pswitch pswitch-joined
 Playback channels: Front Left - Front Right
 Limits: Playback 0 - 255
 Mono:
 Front Left: Playback 217 [85%] [-19.00dB] [on]
 Front Right: Playback 217 [85%] [-19.00dB] [on]

I played a couple 16/44.1 FLAC tracks and I'm not hearing any distortion when my downstream Amp volume control was cranked up to loud volume levels. The DAC is an Allo Katana.

You are welcome to zip up the track and send me a download link and I'll see if I can repro.

You might also want to open alsamixer and see if it reports the same gain as the amixer command.