DisplayPort not recognized

[MR ZenWiz]

Update:

I went through about half the steps in the Ubuntu sound
troubleshooting page
(https://help.ubuntu.com/community/SoundTroubleshooting) but so far I
haven't found a clue.

20:04 [admar at mar-HP8740w:~] $ sudo aplay -l
[sudo] password for admar:
**** List of PLAYBACK Hardware Devices ****
card 0: MID [HDA Intel MID], device 0: 92HD75B3X5 Analog [92HD75B3X5 Analog]
  Subdevices: 0/1
  Subdevice #0: subdevice #0

I won't show the full list of lib/modules drivers as it is fairly
extensive (unless someone thinks the answer might bet therre...).

20:06 [admar at mar-HP8740w:~] $ sudo lspci -v | grep -A7 -i "audio"
00:1b.0 Audio device: Intel Corporation 5 Series/3400 Series Chipset
High Definition Audio (rev 06)
Subsystem: Hewlett-Packard Company 5 Series/3400 Series Chipset High
Definition Audio
Flags: bus master, fast devsel, latency 0, IRQ 47
Memory at d7420000 (64-bit, non-prefetchable) [size=16K]
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
20:07 [admar at mar-HP8740w:~] $ sudo lsmod | grep snd
snd_hda_codec_hdmi     49152  1
snd_hda_codec_idt      57344  1
snd_hda_codec_generic    73728  1 snd_hda_codec_idt
snd_hda_intel          36864  5
snd_hda_codec         126976  4
snd_hda_intel,snd_hda_codec_idt,snd_hda_codec_hdmi,snd_hda_codec_generic
snd_hda_core           81920  5
snd_hda_intel,snd_hda_codec,snd_hda_codec_idt,snd_hda_codec_hdmi,snd_hda_codec_generic
snd_hwdep              16384  1 snd_hda_codec
snd_pcm               102400  5
snd_hda_intel,snd_hda_codec,snd_hda_core,snd_hda_codec_hdmi
snd_seq_midi           16384  0
snd_seq_midi_event     16384  1 snd_seq_midi
snd_rawmidi            32768  1 snd_seq_midi
snd_seq                65536  2 snd_seq_midi_event,snd_seq_midi
snd_seq_device         16384  3 snd_seq,snd_rawmidi,snd_seq_midi
snd_timer              32768  2 snd_seq,snd_pcm
snd                    77824  20
snd_hda_intel,snd_hwdep,snd_seq,snd_hda_codec,snd_hda_codec_idt,snd_timer,snd_rawmidi,snd_hda_codec_hdmi,snd_hda_codec_generic,snd_seq_device,snd_pcm
soundcore              16384  1 snd

Here is what pavucontrol lists for the configuration options for the
sound with the headset (speakers) unplugged):

Analog Stereo Duplex
Analog Stereo Output
Analog Surround 4.0 Output + Analog Stereo Input
Analog Surround 4.0 Output (unplugged)
Analog Stereo Input
Off

Al of this was with the DP-HDMI adapter plugged in and connected to the HDMI TV.

For the record, the sound through the speakers with the Analog
Surround 4.0 Output + Analog Stereo Input was much more brilliant and
sounded pretty decent for laptop speakers, but that's not an
acceptable substitute or solution.

I also tried to do the sound reinstall with aptitude, but for some
reason aptitude can't find the generic kernel image or modules for the
installed kernel (Linux mar-HP8740w 4.10.0-32-generic
#36~16.04.1-Ubuntu SMP Wed Aug 9 09:19:02 UTC 2017 x86_64 x86_64
x86_64 GNU/Linux).

I don't really need the HWE kernel if that's the problem, but I have
no clue (drivers ahve never been my area of specialty).

Thanks, I hope.