On 02/03/2015 19:45, Teemu Likonen wrote:
But with high-dynamic classical music I need to turn amplifier's volume up more than usually and it reveals some sort of digital noise. Here's a short recording of the sound (file size 1.2MB): http://koti.kapsi.fi/~dtw/usb-dac-digital-noise.flac That's from my Debian 7.8 box. But when I use the DAC device in my Macbook Air (OS X) and play the same music files, there is no noise. So I think it must be my Debian software stack or a hardware issue.
Gosh, that's a terrible noise. Sounds as though it has two components, as well. One noise sounds to me as though there might be another live 'input' feeding into the mixer stuff. Such an input might not be 'terminated' with a microphone (or might be, and is picking something up).
Is your D7 box a 'system' box or a laptop? Presumably, the D7 box has some built-in 'soundcard', maybe on the mother board. I was wondering if it is possible to completely disable the built-in soundcard, in the BIOS.
I also have a USB DAC but I haven't run it on D7, neither on a laptop nor on a system box. My DAC device also has 'inputs' (2 x RCA). If your device has inputs, can you check that the 'mixer' does not have the USB 'inputs' active? (Even if they are totally 'turned down', it would be better to have them 'off', if that is possible.)
Summarising, check for other 'inputs', and make sure they are disabled and not being 'mixed in'. You could, also, plug the USB DAC inputs (if any) into some piece of HiFi so that they are actively 'terminated' - in case there is an issue with some kind of interference pick-up. (The higher tone in your file is similar to an interference I get with one of my audio devices.)
I'm not great on the command line, so I cannot help with the CLI to needed to manipulate the sound stuff.
regards, Ron