RPi 2 noise problem only with FLAC files

[tangoo]

Hello guys,

Setup:
- RaspberryPi 2
- Raspyplay4
- Amp at 100%

-> When I play files with HW-volume control setting there is no noticeable noise on my speakers with any file formats.
However, I would prefere using software volume control in order to set the volume "linear" with my mpd clients and have a wider volume range.
This also works fine with no noticeable noise as well!
-> But only when playing any MP3, WAV or FLAC with higher bitrate / Hz than 16 / 41000.

Problem:
FLAC files with 16 / 41000 have an audible noise level wich stays the same from software volume 1% to 100%.

So my conclusion is a Software/communication "problem".
Any clue why this appears and what tweak could help?

Thanks for any help.
Stef

[tangoo]

Hey everyone,

I can confirm that this also appears with RPi 1 B+ and with different constelations of amps and power supplies and with HifiberryDAC+.
It is significantly reduced (gone) by lowering the max hw volume to about 70 % before switching to sw volume, this will set the max sw volume dB output of DAC to the last state hw volume was. By the way this is the reason why having not the same "max output anymore" when switching between sw/hw volume and testig constellations, if anyone was suffering from this as well before and thinking that he broke his DAC

However, a solution that I can live with is to just use hw-volume. This is even better to control music in the evening when you dont't want to annoy your neighbors

Greets
Stef