Whilst I'm not surprised by this result, the amount of code restructuring that took place makes it hard to nail things down. Does this machine have multiple output jacks? Including front panel? Can you try plugging speakers into different jacks to see if it's a jack configuration issue?
HYPERFIRE is one of my custom built machines, built from the ground up, so I know it rather intimately.
It contains an ASUS F1A75-V Pro Motherboard, with an AMD quad core CPU (forget the specific model). The ALC892 chipset is built-in on the motherboard.
I have liked using ASUS motherboards for years, because of their excellent, well laid out User manuals, both graphically and verbally (something highly appreciated by method engineering professionals like myself

). Its very difficult to go wrong following an ASUS manual, for assembly or other purposes.
As to audio connectors the motherboard has a standard set of High Definition Audio connectors (coloured orange, black, grey, light blue, lime and pink) on the back of the motherboard only, and was connected to the Bang and Olufsen stereo system on the monitor with a single cable plugged into the standard green connector. Therefore it was relatively easy to swap the single cable for the 5:1 surround sound cables (orange, black and lime), attaching them to the appropriate connectors on the motherboard.
Using the modified 3.9.11 0220 driver, I was able to generate surround sound, something I was not able to do with the legacy ArcaOS 5.0.6 driver based on the legacy ALSA code - I tested your latest 0922 driver, Paul, and was still not able to generate any sound.
So I don't really think, Sir that connection to the wrong connectors is the problem, but it pays to be thorough, so I've now confirmed that.
As you know I consider myself a lateral thinker, so I thought I'd spend some time coming at this from a different angle - namely, have we ever asked the questions as to whether the Linux community had problems with this chipset before?
Well, they did .......... and 54 others as well.
I spent some time on search engines, which sent me to various Debian and Fedora and other Linux sites. I can send you the links if you wish, Paul, but I attached a couple of text files down below, that you and others might be interested in.
I will say that trolling quietly (fishing wise) through a linux forum reminded me of Physics lectures of 40 years ago - a lot of esoteric information, technical references, some arguments, and a lot of debate (and I'm not in anyway dissing any of you who are part of said community - its just that, looking in, the Linux forums are an experience unto thyself

)
One item that struck me, referenced four times was mention of "auto-mute" - is there any reference to that in any of the PCI/HDA source code?
It seemed that switching "auto-mute" off (the default seemed to be "on") seemed to solve the no sound problems for various people - the problem is, the forum contributors really didn't say where?
There were references to "AlsaMix", "PulseSound" and "Audacity" of which I've only heard of the last, but I assume they are mixer programs similar to PMUnimix. But not sure if the discussions were recommending adjusting "auto-mute" through there or not.
But it also gave me the possible mad hypothesis that, because this was such a problem, perhaps it was solved in a later release of the Linux kernels v3 or above, so downloaded and tried your 3.14.9 and 4.0.9 builds and installed them - sadly no change and no sound.
Its difficult for me to tell how long ago in the Linux development all that occurred, Paul, so perhaps I caught a red herring <sic>, but you may have a better idea as to where you might scrounge up some linux based changelogs to see whether and when linux developers might have done something, which may not be included in a source file your using.
I can't believe that it would still bee a problem they have not addressed in their kernel for possibly 55 sound chipsets. As an aside, it also might be worthwhile, if their is anyone who has not gotten their sound to work with your drivers to try the latest V3 kernel derived driver that worked for me - that would be contained Uniaud32-3.9.11-20220920.zip - the list of chipsets that had problems is part of what is in the first text file below.
Anyway just another of my mad musings on the subject of lateral thinking Sir and a fine weekend to you!
M