using linux to send usb audio to external DAC

[marko]

Any other audiophiles in here?

I have a Stello DA-100 DAC, this DAC has a USB input for
PCM digital audio. I've read on various audio sites
posts from people mentioning that linux can be used
to send audio into a DAC like this but they don't go into
details. My question is, if I have a DAC with a USB input,
and on the linux box I have either FLAC or WAV files,
how do you send those to the DAC via usb?

In the windows platform, I think this do this with
something called ASIO4ALL, I'm trying to dig
up the same or similar for linux.

Mark

[lupin..the..3rd]

Hi Mark, were you able to make this work? I've just placed an order for the Stello DA-100 and I'd like to use it with my Linux box. Not much to be found on the internet regarding this device & linux.

I imagine I could just use some Linux supported sound card with SPDIF output and run that to the Input on the DA-100. I'd prefer to avoid the potential jitter and signal sync issues and just plug the DA-100 in directly using the USB port. Dunno if Linux will play nice with it tho.

Anyone else have one of these?

[marko]

Lupin
No, I found too little info on how to do it, I just use the DA100 as an ordinary
DAC. I run my coaxial digital output from my ancient 1989 vintage Luxman CD player
into it and it works great. Actually my real main CD player is a EAD Dvdmaster
which is really a DVD player but's also really good at redbook CD too, I'd like to
try it next because it has a higher bit rate digital output and can read dvd audio
disks. But it's less convenient because I wanted to listen to usb music at my
computer desk and not in the main tv/audio room. For speakers I'm running
the DA100 into a Stello headphone amp, it serves the job of a preamp
and then drives a pair of NHT M-00 powered speakers. I use a Grado SR80
for headphones.
About not much being on the internet about the DA100 and linux,
since usb dac's frequently are pretty similar about how they work
maybe it's ok to read a help page about using linux, usb and
a different make of DAC.

I suspect the way to do this usb streaming might be Jack:

http://en.wikipedia.org/wiki/JACK

but jack seems made to connect software inside linux together
and not stream audio to the usb port and out.

Then I go find a post like this

(notice posts #3 and #5)
http://www.head-fi.org/forums/showthread.php?t=154710

which suggests that all you need is usb -audio support,
Linux has that for sure but we need a good how-to if
it does work.

Mark

[lupin..the..3rd]

Mark,
My setup will consist of the Stello DA-100 connected to a pair of ADAM Audio A7's with AudioQuest Scarlet Viper interconnect.

From what I've been reading, it's somewhat common for laptops to send quite a bit of noise out over the USB. Dells in particular seem to have noisy USB bus. The fix is to use a cheap USB sound card with SPDIF optical output and run that to the DAC. There are several such USB sound cards that work with Linux.

Once my DA-100 arrives, I'll play with it a bit and see what I can get working...

[lupin..the..3rd]

Well, the DA-100 arrived and it appears to be plug-n-play! I plugged in the USB port, and an 'lsusb' reports a Texas Instruments device. I started ALSA with the generic USB-Audio driver, played an MP3 and I had music! That easy.

There's no volume adjustment however. alsamixer shows a single 'PCM' volume adjustment but moving it up or down has no effect. I guess the volume control on an external amplifier is required.

Edit: Been doing some reading, and apparently that's the norm for any generic USB DAC or SPDIF output that the volume is at a fixed output level. I just ordered the Stello HP-100 preamp which will provide the volume control.

This seems like a nice Linux-friendly hifi setup!

Edit 2: I'm using Gentoo, not Fedora. Under Gentoo, I add a line 'ALSA_CARDS="usb-audio"' to my /etc/make.conf and re-compile the alsa-driver and alsa-tools packages to enable the usb-audio support. I don't know how you do this in Fedora.

Edit3: I'm using a sound blaster live USB to send SPDIF audio to the Stello DA100. I like the fact that it's electrically isolated that way. I'm also now using an hp dv9500t laptop. Here's a page I made for its Linux compatibility: http://home.earthlink.net/~george164...t/dv9500t.html

[marko]

lupin:
(I know this is a super old post but...)

Well , I finally did this too, I have Fedora 13 and tried my Stello DA100 DAC via usb,
it works but I had to try three different PCs because there's so much electrical garbage noise coming into the DAC by the USB cable. Did you have noise problems? Does it help to run the usb through a hub?

I was also able to play internet radio via rhythmbox into my DAC, that was really neat,
I didn't know that would even work.

Mark

[mndar]

Old Old Thread Indeed!

Originally Posted by lupin..the..3rd

There's no volume adjustment however. alsamixer shows a single 'PCM' volume adjustment but moving it up or down has no effect. I guess the volume control on an external amplifier is required.

I have Creative USB X-Fi. Since it has no hardware mixers, I use softvol with dmix to get a volume control with alsamixer.
Dmix also allows multiple applications (Flash/Amarok/Mplayer etc) to use the audio simultaneously. I need ~/.asoundrc for that.

pcm.!default {
    type            plug
    slave.pcm       "softvol"   #make use of softvol
}

pcm.softvol {
    type            softvol
    slave {
        pcm         "dmix"      #redirect the output to dmix (instead of "hw:0,0")
    }
    control {
        name        "Master"       #override the PCM slider to set the softvol volume level globally
        card        0
    }
}

Originally Posted by marko

Did you have noise problems? Does it help to run the usb through a hub?

marko, I don't have the Stello DA100 but I guess low power could explain some problems.

[marko]

mndar
I found some apps will do volume control, for example playing last.fm in Firefox into the DAC by usb, the volume slider worked. But in Amarok streaming internet radio the volume control in amarok wasn't doing anything. Also if you go into pulseaudio configuration and set the profile on the DAC to "digital stereo IEC958" the volume control in pavucontrol then can control the volume but if you set it to "analog stereo output" the volume is just fixed. Since the IEC958 seems to sound fine I'll leave it there.

[marko]

Originally Posted by marko

lupin:
(I know this is a super old post but...)

.... I had to try three different PCs because there's so much electrical garbage noise coming into the DAC by the USB cable. Did you have noise problems? Does it help to run the usb through a hub?

Mark

Wow, switching to my Sony Vaio which has a simple two prong non-grounded plug instead of the 3 prong plug on my Asus laptop totally fixed the buzz/noise problem.

However this not a very good fix because I really want to use this desktop PC I have laying around and not my nice portable Vaio to stream to this dac.

[LaKing]

The noise comes from some kind of ground circulation. Some kind of "Ground loop".

USB cannot transfer noise as digital data. The noise gets generated in the DAC in the analog way.

A common solution is to use battery on laptop, or a 2 pin electric connector, or eventually isolate the shield on the power connector, which is not really recommended.


More professional desktop-friendly solution is to use optical cable, or electric SPDIF (coax RCA cable) with professional conversion, which is okay too.
In my setup USB travels 10 meters thru hubs and cables, to an SB external, from there Coax to a Motu828 ( the firewire is not connected at all ), and then the DAC makes the Job. ...
.. no driver problems, no noise, clear digital sound.

If I do this 10m distance the analog way, you can hear where the mouse is on screen, and when the CPU calculates something.

[marko]

Originally Posted by LaKing

The noise comes from some kind of ground circulation. Some kind of "Ground loop".

USB cannot transfer noise as digital data. The noise gets generated in the DAC in the analog way.

I disagree with that, analog noise from the laptop's bad power brick can be carried down the usb ground shield into the dac and pollute the input of the analog section of the DAC. I agree the digital domain stuff is ok.