Excellent work, many thanks, a very nice starting point for people with interest.
Manjaro is IMHO also a good pick for a rolling release.

Sorry to hear about bad audio quality and delay when watching videos.
But, if this can't be fixed, where is the advantage of Linux over Windows?

You claim Windows is garbage and instabilities on Windows, but I had no BSOD since Windows 7 (maybe around 10-15y)
and Windows is still one of the two major platforms for DAW work.
Yes, I also dislike Windows 11, but it also doesn't help if Linux is not a real alternative for professional audio work,
if audio quality is not at 100% and low latency is also a strong requirement.

Don't get me wrong, I am not against Linux (I started with Unix a few decades before as pro) or your solution.

I mention this only because you are doing Windows / Windows 11 bashing and claiming Linux would be the better solution, but sorry, this is really not the case, at least not under a professional perspective.

My personal experience, in short: over time, I got more and more application requirements that cannot be fulfilled by Unix / Linux. Additionally, it takes too much time to get all working.
Definitively not helpful is, that over 200 Linux distros exist where every team has another idea about system setup and operation and which combination of open-source packages they use.
Another big issue is, that documentation on the internet (Wikis and what not) is not up-to-date, and you need to experiment. In some areas, you simply need to become a Linux nerd to get things working, or not.

As nice as Unix (not necessarily Linux) is… In the datacenter area, it can shine with the proper distribution and if people know how to operate it. For private use, it can also be pleasant, to get a box up for simply browsing the internet.
But if you want more than such trivial things, then it can become much harder to operate and get a satisfactory solution compared to Windows and Apple. It's this high level of customization which can cause issues of its own, and the many differences between distributions make it additionally harder to operate and support (esp. for companies offering products).

For audio / video / DAW work, I think that you are still better off to use Windows or Apple. Most people do not have time for such customization under Linux. And I have to admit, also for me (even as Unix pro), it's much easier and more pleasant to use a Windows environment where most things are much easier to implement.

If you want to compete with Windows / Apple and want to become a real alternative, then you need to be better, and this you can only achieve with a certain level of standardization. In my opinion, it was a fault of Linus that he only concentrated on the kernel and didn't deliver a complete OS, this bazaar style of distributions allows for too many deviations and issues of its own.

For audio professionals who run a business using commercial software, you need a stable platform which is fully supported in terms of hardware and applications. This is also my preference, even if it's “only” a hobby, as I want to avoid wasting too much time on unnecessary things.

More "stably on Linux"? You obviously don't know what you're talking about starting with what is "Linux".

This is not about being hostile to open source desktop OS but to realize the needed support and stability to be able to do the work that is needed to be done to make a living. For most people an OS is just a tool using the applications they need to get that done, and for desktop a Linux distro is in many (most?) still a poor match.

That said, I started programming as a teenager around 40 years ago and have seen many computers, OS, programming languages since then. I even used SUSE (a Linux distro) for desktop for several years, followed by OpenBSD and FreeBSD. A decade ago I switched to Windows for needed applications for desktop usage but still used OpenBSD as well as Linux for server usage, mostly at work.

The various *BSD flavours, like OpenBSD and FreeBSD, are a much better experience than Linux for desktop where it not for needed HW drivers (like graphics cards). The documentation, especially for OpenBSD, is excellent. For Linux: Piss poor, to put it mildly. The WWW is filled with awful Linux HOWTO's.

I certainly understand why RME does not officially support Linux with their own drivers, including TotalMix FX and DigiCheck: A support nightmare.

They have in the past helped developers with info/code to make drivers. Perhaps RME can publish more info as to make it easier for others to make their own drivers and duplicate TotalMix FX. Perhaps make improvements to their Class Compliance to make their devices work more comprehensively/better on OS like Linux. My guess is that you'll have much more success with that than requesting RME Linux drivers.

Why would you move on to another art form because others don't agree with your choice of Linux distro? To me this seems to be that the tools themselves are most important to you and not the art (i.e. what you create). I'm not an artist/musician but do find this perplexing as the tools in this case appears to be digital only.

I understand perfectly well what you are trying to say with respect to Linux support for your needs/wants, and as I wrote above above I've been around for a number decades in programming (including for open source). What I think you don't understand (from reading your post on LinuxMusicians that you linked to) is that a project, like "AV Linux", is a voluntary endeavour by people doing it on their free time with no pay. In this case, a single developer, who obviously cared about this for a very long time and spent very many hours on it. Then you want other developers to contribute to this project, also on their free time, for your needs, never mind what they want to spend their own unpaid time on. It's no surprise that your pitch fell flat.

I don't have any USB RME devices and currently only have my Fireface400 plugged in via firewire.

Forgive updating a rather old forum post but I was hoping someone might have mirrored the original documentation linked in the initial post? It seems the github links are no longer active.

Trying to get an RME HDSPe working on Linux. Works great on Windows 10 (as an aside, wow is TotalMix good! First time I've used it and it blows everything else I've used to this point completely out of the water).

On Linux, however, I've built the driver and tools via (https://github.com/PhilippeBekaert/snd-hdspe/pulls) and can see it in ALSA. However PulseAudio doesn't seem to like it as it has >32 channels. I'm not sure how to get around that. Initially for Linux I just wanted to have desktop audio out as the line out beats the pants off my integrated sound card and that would let me route fewer wires to my studio monitor mixer from my PC. A second bonus is I could start messing with Reaper for doing mixing or analog mixdowns but that's for another day (and I suspect I might have less problems with Reaper itself than getting desktop audio working).

Welcome to thoughts/suggestions!