LinuxQuestions.org - arecord recording silence, but I can hear sound!

I'm trying to record sound via my line-in input on my soundcard using arecord. The sound is clearly getting in there somehow, as it is being looped through to the line-out so I'm hearing it. But using arecord I just get silence.

I type:
arecord -f cd --file-type raw --device=default tmp.sig
to record the sound to a raw file, but it's just full of zeros.

I've also tried recording in audacity with no joy, just silence.

If I do "arecord -l" I get:

Code:

**** List of CAPTURE Hardware Devices ****

card 0: CMI8738MC6 [C-Media PCI CMI8738-MC6], device 0: CMI8738-MC6 [C-Media PCI DAC/ADC]

  Subdevices: 1/1

  Subdevice #0: subdevice #0

card 0: CMI8738MC6 [C-Media PCI CMI8738-MC6], device 2: CMI8738-MC6 [C-Media PCI IEC958]

  Subdevices: 1/1

  Subdevice #0: subdevice #0

In alsamixer line-in is selected, and I've un-muted both the line input and mic input (I've also tried with mic muted).

I'm running Ubuntu 7.10 with kernel 2.6.22-14-generic

Any ideas to unblock my PC's ears?