Good news. I was planing on contact them also, and will do so tomorrow.
There is strengh in numbers, they say… 
My request for info from Cambridge has been forwarded internally to the DAC engineers.
Other DAC companies are chasing kernel.org to get their DACs supported in front of their competition, Cambridge is in no hurry.
This is the answer I got from customer service:
We have already passed your feedback through to our engineering team and I am assured that your case will be reviewed at their next meeting and taken into consideration when planning future firmware and app/product updates. Your proposal is certainly possible in theory, but at the moment it is not currently scheduled as a project for the engineering team, and any such project would need to be scheduled with consideration to how it will impact priorities for current projects.
Such a little piece of admin work (getting a quirk added to the usb audio driver), they do not have to bother any development team.
The quirk is one line of predefined code in a kernel module.
It as a shame, a way of saying “we’re not interested”.
Note:
Only thing I can offer is support for community portings and x86, for some of those we maintain our own kernel and the quirk can be added.
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I’ve got the same answer…
I did ask them for an explanation after giving more details about the little work it means to them and advised also to inform their DacMagic product manager about what we were told 
There is nothing much Volumio can do, sorry. I’ll post in case there is anything new.
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After another member managed to get DSD led on the 200M (see this topic), I’ve tried again and this is what I’ve got, as posted on the other topic:
@gkkpch , do you have any possible explanation, by any chance?
TIA
this is extremely difficult to believe.
To make sure I don’t tell fibs by missing updates, I did check the current kernel version of the PI once more (actually also right up to the just just released 5.14 kernel), there is no mention of support for the 200M yet.
It is impossible a device can support DSD raw/ direct/ native features if that very device has not been registered in the usb quirks table of the usb audio driver. The driver will not be told it has DSD raw capabilities, so won’t send the raw streams. Yes, the DAC works, probably also sounds terrific (to be expected from Cambridge when implementing the ess chip), but surely defaults to “dsd over pcm”, which is not the same.
I don’t have a 200M and can’t verify what the leds are doing when using DOP, but if Cambridge already admits that they have not registered (which I confirmed, see above) and consider it (perhaps) as future task for the development team then someone is telling fibs in the linked thread you mentioned.
Thanks for your reply!
First, the 200M do sound fantastic!
The weird thing is that I can also set DSD Direct on Volumio and it shows the correct leds. But only if everything is done on a certain order. And after playing a no-DSD file, it stops showing the correct leds on DSD files.
I have a pretty busy week but I 'll try to come back to this issue on the weekend and post the correct steps to get the 200M leds reporting the correct file type and sample rate.
Again, I’m not really missing any sound quality, and even doubt I could hear the diference, but this kind of misbeahviour really bothers me, so I’ll try to at least understand it, even if there’s nothing I can do to correct it.
So, there is no way that Raspberry/Volumio could send DSD to the 200M?
I’m absolutely sure that I saw the DSD light with the correct sample rate in a few diferent files. And I’m almost sure I can reproduce it, next weekend.
When you do, please let me know what the content of the hw_params file is while you’re playing (you need to find a way through the /proc/asound tree, fairly easy and self explaining, go the pcm0p way when your in the right card folder…
Will do!
Cambridge DAC 200M will now play DSD direct on x86 and Odroid N2 with version 3.252 and newer.
Any ETA for the raspberry? I’ve been out of town and too busy to get back to this, as promised…
No, x86 and Odroid kernel changes I did myself and sent the patches to Cambridge, including the email address of the maintainer for the kernel usb audio driver. They promised to follow up with the guy to get it into the official releases (stable and LTS).
No idea whether and when they will do this, they tend to promise a lot, but at least this time they were listening and understood.
I’ve done my part for the community (and myself, own one now and very pleased with it).
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Some bad news, Cambridge just informed me that they do not see this as a priority. So it is very unlikely, that the patch will end up in an official kernel any time soon. In fact, I believe it will never get done, linux users are not interesting enough for them.
Their quote: “From our own inbound communication from customers, we have not seen a high demand for this at the moment”.
So DSD direct support will remain limited to the x86 and Odroid N2/N2+ platform for a while to come.
Perhaps when more of us ask about this problem, there will be some reaction from Cambridge Audio.
Previously, I asked them about extending the functionality of DacMagic100 with MQA and the answer was equally disrespectful, until after some time a DacMagic200 fully supporting MQA appeared, so maybe not all is lost and the update will be real
they don’t even have to change hardware or their own software/firmware.
All it needs is a one-line addition to the kernel, 8 gave rhem the patch already, still they don’t see that as a priority, see above.
Anyway, I won’t get involved anymore, does not appear to be worth it.
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Unfortunately, you seem to be right.
I’ll leave them a last message and be done with it also. Fortunately I can play DSD from the PC. It’s not the same, but will have to do…
Thanks for your efforts!
Naturely, in future hardware buys, Cambridge will not be on my short list… plenty of fish in the sea!
Well, just got a Cambridge reply. Fast, nice and writen by a real person, not something taken out of a menu.
That said, it’s not the answer we would like (and they even acknowledge that).
Mainly, they state that a small number of costumers requested official USB Linux compatibility. That the simplicity of the solution is only aparent and they would need to run full tests before releasing it to relevant parties. And that they can not commit to do it or schedule it due to workload and the usual suspects (covid, processor shortage, shipping issues, etc…).
The good part is that they also wrote that the issue is on their wish list and will be addressed sometime in the future.
The bad part is that it has no priority on that wishlist, “sometime in the future” is what I also heard and know from experience what that means with non-priority tasks.
Yep, I don’t have high hopes on 200M. Maybe on a future device… that I almost surely will not buy!