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I've spent the past 2 days working on a new recording/editing computer for the KRUU studio. We've been using Ubuntu Studio x64 & I wanted to upgrade the hardware & provide a dual monitor solution & maintain quaility recording using an M-Audio Delta 44 PCI card. After modificaitons were complete to the case to allow for proper mounting of the components I was pleased to see that the dual monitor worked well.

Unfortuneately, the audio was less than impressive. After install, the audio card was detected incorrectly but was listed as a capture device but not as a playback device. To get Alsa to work with the card properly additional configuration is needed which was to be expected as the same issue was observed in 8.04 described here:

http://www.linuxquestions.org/questions/ubuntu-63/no-sound-in-ubuntu-studio-with-m-audio-delta-44-a-781558/

Add to end of first config section of /usr/share/alsa/cards/Ice1712.conf:

slave.format S32_LE
slave.channels 10

Additionally, pulseaudio needed to be informed to use the card via Alsa in /etc/pulse/default.pa. In my case hw:0 is the device to use as the only other audio was on the motherboard & was disabled in the BIOS but will differ based on computer configuration. To read more about finding the correct entry & background of Linux audio config look at this article: http://ubuntuforums.org/showthread.php?t=843012

# Load Delta 44:
load-module module-alsa-sink sink_name=delta_out device=hw:0 channels=10 channel_map=left,right,aux0,aux1,aux2,aux3,aux4,aux5,aux6,aux7
load-module module-alsa-source source_name=delta_in device=hw:0 channels=12 channel_map=left,right,aux0,aux1,aux2,aux3,aux4,aux5,aux6,aux7,aux8,aux9

# Set the default sink and source (not mandatory, intel-hda
# would probably be used without this):
set-default-sink delta_out
set-default-source delta_in

Though adding the previous lines to 8.04 would provide a functional system this did not result in a working config in 10.04. Pulseaudio would refuse to start with the following error:

I: (alsa-lib)pcm_hw.c: open /dev/snd/pcmC0D0c failed: Device or resource busy

Using fuser -v /dev/dsp* & fuser -v /dev/snd/* provided no results. Killing any applications that could possibly be locking card ended with same results. Permissions were checked & were correct, the device is owned by audio group & my user was included in audio group.

After much searching & headache I finally understood that the problem was due to an issue with pulse & udev based on an old bug described here: https://bugs.launchpad.net/ubuntu/+source/pulseaudio/+bug/557421

Some suggestions to resolve the issue were unacceptable for our uses. To resolve this issue the final piece was to disable udev in /etc/pulse/default.pa.

### Automatically load driver modules depending on the hardware available
#.ifexists module-udev-detect.so
#load-module module-udev-detect
#.else
### Alternatively use the static hardware detection module (for systems that
### lack udev support)
#load-module module-detect
#.endif