OK, here finally are my official instructions for connecting a USB DAC
up to the Touch.
A few words up front: this is not officially endorsed by Logitech, if
you have questions about this, don't bother Logitech support, they
won't have any idea what you are talking about. This is NOT plug and
play, you have to go in and edit a file on the Touch, once you do that,
you cannot get music out of any other output, it will ONLY send music to
the USB DAC. You have to go in and restore things to the way they were
in order to get music out of any other output. The setup will be
different depending on whether you plug the DAC in after bootup (known
as hotplugging) or already plugged in when booting. Choose which way
you want to go and ALWAYS do it that way! (if you forget and get it
wrong, it won't hurt anything, you just won't get any music out) Due to
some weirdnesses in the way USB DACs are seen by the Touch, the UI beeps
and other sounds will usually be turned off when a USB DAC is plugged
in. But not always.
Not all USB DACs will work with the Touch. If the DAC requires a custom
driver, it will NOT work with the Touch. Only DACs that can be used with
generic USB drivers will work. If your DAC can only play up to 48KHz
sample rate you may have problems playing 88.2 or 96 files. The server
thinks the Touch can go up to 96, but if the DAC can only go up to 48,
the linux software on the Touch will do the down conversion, which
takes a fair amount of horsepower and may cause problems with playback.
One other thing, its probably not a good idea to use a USB DAC if you
are also using a USB disk plugged into the Touch to store the music
files. Since there is only one USB port you will need a USB hub,
putting both the storage and the DAC on the same port is probably not a
good idea, it may work, it may not. Be prepared to use an external
server over a network.
So if you are still willing to give this a try, here are the details.
You will need to SSH into the Touch. In order to do this you will need
an SSH client running on a computer on your network. On windows this is
called PuTTy, its free, you can find it on the web. For Mac OSX its
builtin, called SSH.
PuTTy is a regular windows GUI program, when you bring it up you type
in the IP address of the Touch, press <enter>. It will then ask for the
user, type in root<Enter>. Then it asks for the password. (See below)
For SSH on OSX you have to start a command window, then type:
ssh -l root <IP address>
It will then ask for the password.
To SSH into the Touch you have to turn remote access on, this is done
with
settings->advanced->Remote access
Touch the "enable remote access" line, you should see the little square
go blue. You will also get a popup which gives the IP address and the
password, write these down. These will be used when you SSH into the
Touch.
Now plug the USB DAC into the Touch and reboot the Touch (or reboot and
plug the DAC in) Pull the power plug and reinsert it to reboot.
When up and running SSH into the Touch (see above). (for each line you
see in these instructions type <Enter> at the end of the line)
Type:
aplay -l
(thats dash ell)
This gives you a list of the audio devices on the Touch. You should see
the USB DAC. Each device will have a line starting with
card <number> <name>
such as
card 3 USB <lots of other stuff>
The name is the one you want to write down. In this case it was USB. It
might be something such as "default". In this case the rest of the line
will let you know its the USB DAC.
Then type:
cd /etc
cp asound.conf asound.conf.orig
sync
Now you are going to create a new config file. The only editor
available is "vi", which is very weird to use if you have not used it
before. It runs in a display mode (default)and an insert mode. You get
into insert mode by tapping the 'i', type stuff you want, then tap
<ESC> to get out of insert mode. When in display mode tapping 'x' will
delete the character the cursor is under. Tapping 'dd' will delete a
line. That should be enough to edit this simple file. In the file below
replace <name> with the name you wrote down in the previous step. For
example
card USB;
Type:
vi asound.conf.usb
tap 'i', type:
pcm.usbdac {
type hw;
card <name>;
}
pcm.plugusb {
type plug;
slave.pcm "usbdac";
}
ctl.plugusb {
type hw;
card <name>;
}
pcm.!default plugusb
Tap the <ESC> key
type:
:wq<enter>
(thats <colon><w><q><enter> don't forget the colon)
To quite without writing anything type:
:!q<enter>
This will write the file and quit.
Then type:
cp asound.conf.usb asound.conf
sync
sync
(the syncs make sure memory buffers get written to disk)
Type:
exit
This gets you out of SSH.
At this point reboot the Touch and the music should now play through
the USB DAC. Since you explicitly told the music to go to the USB DAC
you won't have any sound when the USB DAC is not connected to the
Touch. To get back to normal you have to SSH back into the Touch and
type:
cd /etc
cp asound.conf.orig asound.conf
sync
sync
exit
And reboot. You should now be back to normal.
If things get so badly messed up you don't know what to do you can
always do a factory reset which will undo all this.
Thats about it. Have FUN!
PS, there IS a way to get music out of all the other outputs and a USB
DAC at the same time, but its a WAY more complicated setup, I decided
NOT to post that.
John S.
--
JohnSwenson
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