I take that back. Didn't need to go home to test it. Still only detecting the HDMI interface.

In my dmesg I get these errors relating to HDA:

myth@Wakko:~$ dmesg | grep -i hda
[    9.811591] hda-intel: unable to grab IRQ 0, disabling device
[    9.811608] HDA Intel: probe of 0000:00:14.2 failed with error -16
[    9.811625] HDA Intel 0000:01:05.1: PCI INT B -> GSI 19 (level, low) -> IRQ 19
[    9.811660] HDA Intel 0000:01:05.1: setting latency timer to 64

alsa-info.sh output:

!!################################
!!ALSA Information Script v 0.4.56
!!################################

!!Script ran on: Fri May  1 16:49:18 UTC 2009


!!Linux Distribution
!!------------------

Ubuntu 9.04 \n \l DISTRIB_ID=Ubuntu DISTRIB_DESCRIPTION="Ubuntu 9.04"


!!Kernel Information
!!------------------

Kernel release:    2.6.28-11-generic
Operating System:  GNU/Linux
Architecture:      x86_64
Processor:         unknown
SMP Enabled:       Yes


!!ALSA Version
!!------------

Driver version:     1.0.18rc3
Library version:    1.0.19
Utilities version:  1.0.18


!!Loaded ALSA modules
!!-------------------

snd_hda_intel
cx88_alsa


!!Sound Servers on this system
!!----------------------------

Pulseaudio:
      Installed - Yes (/usr/bin/pulseaudio)
      Running - No

ESound Daemon:
      Installed - Yes (/usr/bin/esd)
      Running - No


!!Soundcards recognised by ALSA
!!-----------------------------

 0 [HDMI           ]: HDA-Intel - HDA ATI HDMI
                      HDA ATI HDMI at 0xfdffc000 irq 19
 1 [CX8801         ]: CX88x - Conexant CX8801
                      Conexant CX8801 at 0xf9000000


!!PCI Soundcards installed in the system
!!--------------------------------------

00:14.2 Audio device: ATI Technologies Inc SBx00 Azalia (Intel HDA)
01:05.1 Audio device: ATI Technologies Inc RS780 Azalia controller
03:06.0 Multimedia video controller: Conexant Systems, Inc. CX23880/1/2/3 PCI Video and Audio Decoder (rev 05)
03:06.1 Multimedia controller: Conexant Systems, Inc. CX23880/1/2/3 PCI Video and Audio Decoder [Audio Port] (rev 05)
03:06.2 Multimedia controller: Conexant Systems, Inc. CX23880/1/2/3 PCI Video and Audio Decoder [MPEG Port] (rev 05)


!!Advanced information - PCI Vendor/Device/Susbsystem ID's
!!--------------------------------------------------------

00:14.2 0403: 1002:4383
	Subsystem: 1458:a022
--
01:05.1 0403: 1002:960f
	Subsystem: 1458:960f


!!Modprobe options (Sound related)
!!--------------------------------

snd-atiixp-modem: index=-2
snd-intel8x0m: index=-2
snd-via82xx-modem: index=-2
snd-usb-audio: index=-2
snd-usb-us122l: index=-2
snd-usb-usx2y: index=-2
snd-usb-caiaq: index=-2
snd-cmipci: mpu_port=0x330 fm_port=0x388
snd-pcsp: index=-2
snd-hda-intel: probe_mask=1


!!Loaded sound module options
!!--------------------------

!!Module: snd_hda_intel
bdl_pos_adj : 32,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1
enable : Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y
enable_msi : 0
id : <NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>
index : -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1
model : <NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>,<NULL>
position_fix : 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
power_save : 0
power_save_controller : Y
probe_mask : 1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1
single_cmd : N

!!Module: cx88_alsa
debug : 0
enable : Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y,Y
index : -2,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1


!!HDA-Intel Codec information
!!---------------------------
--startcollapse--

Codec: ATI ATI RS690/780 HDMI
Address: 0
Vendor Id: 0x1002791a
Subsystem Id: 0x791a00
Revision Id: 0x100000
No Modem Function Group found
Default PCM:
    rates [0x40]: 48000
    bits [0x2]: 16
    formats [0x1]: PCM
Default Amp-In caps: N/A
Default Amp-Out caps: N/A
GPIO: io=0, o=0, i=0, unsolicited=0, wake=0
Node 0x02 [Audio Output] wcaps 0x201: Stereo Digital
  Converter: stream=0, channel=0
  Digital: Enabled
  Digital category: 0x0
Node 0x03 [Pin Complex] wcaps 0x400381: Stereo Digital
  Pincap 0x00000094: OUT Detect HDMI
  Pin Default 0x18560010: [Jack] Digital Out at Int HDMI
    Conn = Digital, Color = Unknown
    DefAssociation = 0x1, Sequence = 0x0
  Pin-ctls: 0x40: OUT
  Unsolicited: tag=00, enabled=0
  Connection: 1
     0x02
--endcollapse--


!!ALSA Device nodes
!!-----------------

crw-rw----+ 1 root audio 116, 5 May  1 10:42 /dev/snd/controlC0
crw-rw----+ 1 root audio 116, 7 May  1 10:42 /dev/snd/controlC1
crw-rw----+ 1 root audio 116, 4 May  1 10:42 /dev/snd/pcmC0D3p
crw-rw----+ 1 root audio 116, 6 May  1 10:42 /dev/snd/pcmC1D0c
crw-rw----+ 1 root audio 116, 3 May  1 10:42 /dev/snd/seq
crw-rw----+ 1 root audio 116, 2 May  1 10:42 /dev/snd/timer


!!Aplay/Arecord output
!!------------

APLAY

**** List of PLAYBACK Hardware Devices ****
card 0: HDMI [HDA ATI HDMI], device 3: ATI HDMI [ATI HDMI]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

ARECORD

**** List of CAPTURE Hardware Devices ****
card 1: CX8801 [Conexant CX8801], device 0: CX88 Digital [CX88 Digital]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

!!Amixer output
!!-------------

!!-------Mixer controls for card 0 [HDMI]

Card hw:0 'HDMI'/'HDA ATI HDMI at 0xfdffc000 irq 19'
  Mixer name	: 'ATI ATI RS690/780 HDMI'
  Components	: 'HDA:1002791a,00791a00,00100000'
  Controls      : 4
  Simple ctrls  : 1
Simple mixer control 'IEC958',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [on]

!!-------Mixer controls for card 1 [CX8801]

Card hw:1 'CX8801'/'Conexant CX8801 at 0xf9000000'
  Mixer name	: 'CX88'
  Components	: ''
  Controls      : 3
  Simple ctrls  : 2
Simple mixer control 'Playback',0
  Capabilities: volume pswitch pswitch-joined
  Playback channels: Front Left - Front Right
  Capture channels: Front Left - Front Right
  Limits: 0 - 63
  Front Left: 63 [100%] [0.00dB] Playback [on]
  Front Right: 63 [100%] [0.00dB] Playback [on]
Simple mixer control 'Capture',0
  Capabilities: cswitch cswitch-joined
  Capture channels: Mono
  Mono: Capture [off]


!!Alsactl output
!!-------------

--startcollapse--
state.HDMI {
	control.1 {
		comment.access read
		comment.type IEC958
		comment.count 1
		iface MIXER
		name 'IEC958 Playback Con Mask'
		value '0fff000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000'
	}
	control.2 {
		comment.access read
		comment.type IEC958
		comment.count 1
		iface MIXER
		name 'IEC958 Playback Pro Mask'
		value '0f00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000'
	}
	control.3 {
		comment.access 'read write'
		comment.type IEC958
		comment.count 1
		iface MIXER
		name 'IEC958 Playback Default'
		value '0400000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000'
	}
	control.4 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'IEC958 Playback Switch'
		value true
	}
}
state.CX8801 {
	control.1 {
		comment.access 'read write'
		comment.type INTEGER
		comment.count 2
		comment.range '0 - 63'
		comment.dbmin -6300
		comment.dbmax 0
		iface MIXER
		name 'Playback Volume'
		value.0 63
		value.1 63
	}
	control.2 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'Playback Switch'
		value true
	}
	control.3 {
		comment.access 'read write'
		comment.type BOOLEAN
		comment.count 1
		iface MIXER
		name 'Capture Switch'
		value false
	}
}
--endcollapse--


!!All Loaded Modules
!!------------------

Module
radeon
drm
bridge
stp
bnep
video
output
input_polldev
xfs
joydev
uinput
sbp2
ieee1394
lp
or51132
cx88_dvb
cx88_vp3054_i2c
tuner_simple
tuner_types
tda9887
tda8290
tuner
snd_seq_dummy
snd_seq_oss
snd_seq_midi
snd_rawmidi
snd_hda_intel
cx8802
cx88_alsa
cx8800
snd_seq_midi_event
cx88xx
snd_pcm_oss
ir_common
snd_seq
snd_mixer_oss
i2c_algo_bit
compat_ioctl32
videodev
snd_seq_device
snd_pcm
videobuf_dvb
dvb_core
tveeprom
v4l1_compat
v4l2_common
lirc_mceusb2
snd_timer
snd
soundcore
psmouse
videobuf_dma_sg
videobuf_core
btcx_risc
ppdev
pcspkr
i2c_piix4
lirc_dev
snd_page_alloc
shpchp
serio_raw
parport_pc
parport
btusb
r8169
mii
raid10
raid456
async_xor
async_memcpy
async_tx
xor
raid1
raid0
multipath
linear
fbcon
tileblit
font
bitblit
softcursor


Let me know if I can get any other info or test anything else.