OK, that tells me your iMac has an ALC889A.
Hmmm … I can not see any indication of the troubleshooting guide being attempted … One of the early recommendations of the troubleshooting guide is to install alsa-firmware, but I see no evidence of that install in your previous post. Did you install it and remove it? Please install alsa-firmware. Then restart your iMac, and test your audio. And for now leave it installed. I do not know if your iMac requires it, but for the time being, until sound is established, I believe it to be a good idea.
I looked at your mixer settings, and they appear ok for testing.
I saw no mention of the ALC889A in the ALSA-Configuration.txt file for 1.0.18 of alsa. I searched for the ALC889A on the alsa web site, and I did note a series of updates made between 1.0.16 and 1.0.18 of alsa. In particular here: Changes v1.0.16 v1.0.17 - AlsaProject I noted this comment:
ALC889A is recognized ALC885/ALC882 but it's actually closer to ALC888/ALC883
It is possible to apply model options for the ALC885/ALC882 and ALC888/ALC883 codecs.
These options are listed here (from the ALSA-Configuration.txt file):
ALC882/885
3stack-dig 3-jack with SPDIF I/O
6stack-dig 6-jack digital with SPDIF I/O
arima Arima W820Di1
targa Targa T8, MSI-1049 T8
asus-a7j ASUS A7J
asus-a7m ASUS A7M
macpro MacPro support
mbp3 Macbook Pro rev3
imac24 iMac 24'' with jack detection
w2jc ASUS W2JC
auto auto-config reading BIOS (default)
ALC883/888
3stack-dig 3-jack with SPDIF I/O
6stack-dig 6-jack digital with SPDIF I/O
3stack-6ch 3-jack 6-channel
3stack-6ch-dig 3-jack 6-channel with SPDIF I/O
6stack-dig-demo 6-jack digital for Intel demo board
acer Acer laptops (Travelmate 3012WTMi, Aspire 5600, etc)
acer-aspire Acer Aspire 9810
medion Medion Laptops
medion-md2 Medion MD2
targa-dig Targa/MSI
targa-2ch-dig Targs/MSI with 2-channel
laptop-eapd 3-jack with SPDIF I/O and EAPD (Clevo M540JE, M550JE)
lenovo-101e Lenovo 101E
lenovo-nb0763 Lenovo NB0763
lenovo-ms7195-dig Lenovo MS7195
lenovo-sky Lenovo Sky
haier-w66 Haier W66
3stack-hp HP machines with 3stack (Lucknow, Samba boards)
6stack-dell Dell machines with 6stack (Inspiron 530)
mitac Mitac 8252D
clevo-m720 Clevo M720 laptop series
fujitsu-pi2515 Fujitsu AMILO Pi2515
3stack-6ch-intel Intel DG33* boards
auto auto-config reading BIOS (default)
So lets assume the alsa autoprobe upon boot did not recognize the appropriate model for your iMac, and lets try some (all ? ) of the above ONE at a TIME, to see if any help.
So please edit your /etc/modprobe.d/sound file to be as follows:
options snd slots=snd-hda-intel
options snd-hda-intel model=imac24
# u1Nb.2frKzjmhZt4:82801H (ICH8 Family) HD Audio Controller
alias snd-card-0 snd-hda-intel
and restart your iMac’s alsa sound driver by typing in a konsole/terminal su -c ‘rcalsasound restart’ enter root password when prompted, restart your mixer, and test your audio with the speaker test I recommended in my 1st post.
If “imac24” does not work, then try each of the options listed in the above, one by one, until you find one that works. For example, to try “3stack-dig”, replace “imac24” in the /etc/modprobe.d/sound file with “3stack-dig”, restart your alsa sound driver, restart your mixer, and test your audio.
Do that for each model option in the list, until one provides sound.