On my Dell M1530XPS I've recently used the HDMI port. The video function worked but I was not able to get audio support. Had anyone had similar problems?

The digital audio output is registered and under "Sound Preferences" I can select the option "Digital Stereo (HDMI)" but there are no options using alsamixer:
Code:
aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: Intel [HDA Intel], device 0: STAC92xx Analog [STAC92xx Analog]
  Subdevices: 0/1
  Subdevice #0: subdevice #0
card 0: Intel [HDA Intel], device 1: STAC92xx Digital [STAC92xx Digital]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
My video and audio cards are the following:
Code:
01:00.0 VGA compatible controller [0300]: nVidia Corporation G84 [GeForce 8600M GT] [10de:0407] (rev a1) (prog-if 00 [VGA controller])
	Subsystem: Dell Device [1028:022e]
	Flags: bus master, fast devsel, latency 0, IRQ 16
	I/O ports at ef00 [size=128]
	[virtual] Expansion ROM at f4000000 [disabled] [size=128K]
	Capabilities: [60] Power Management version 2
	Capabilities: [68] MSI: Enable- Count=1/1 Maskable- 64bit+
	Capabilities: [78] Express Endpoint, MSI 00
	Capabilities: [100] Virtual Channel
	Capabilities: [128] Power Budgeting <?>
	Capabilities: [600] Vendor Specific Information: ID=0001 Rev=1 Len=024 <?>
	Kernel driver in use: nvidia
	Kernel modules: nvidia-current, nouveau, nvidiafb
Code:
00:1b.0 Audio device [0403]: Intel Corporation 82801H (ICH8 Family) HD Audio Controller [8086:284b] (rev 02)
	Subsystem: Dell Device [1028:022e]
	Flags: bus master, fast devsel, latency 0, IRQ 46
	Capabilities: [50] Power Management version 2
	Capabilities: [60] MSI: Enable+ Count=1/1 Maskable- 64bit+
	Capabilities: [70] Express Root Complex Integrated Endpoint, MSI 00
	Capabilities: [100] Virtual Channel
	Capabilities: [130] Root Complex Link
	Kernel driver in use: HDA Intel
	Kernel modules: snd-hda-intel