Help? Unable to use iPad to DSD USB

I have an unused iPad Mini 4, and would love to get it working with DSD USB, so I can try the Matrix device.
It works as a Roon endpoint, and it plays from Roon via the internal speakers, but I cannot get it to play to USB via either of the Apple “Camera” adapters, no matter what I do.
I’ve tried every combination of settings, Power cycling, and known-good USB cables I’ve got, but the only choice of output Roon offers from the iPad is Speakers. DSD is the latest. The USB display on the DSD shows a green dot, indicating that it sees a USB connection, but the darned iPad does not play to it. iOS is v12.1.4
What am I missing?
(As an alternative, I’d prefer to use a Pixel C Android device, but again, cannot get it to play to USB output.)

Have you tried via an active USB hub?
iPad - Camera adapter - USB hub - Matrix I2s - DS.
iPad - Camera adapter - USB hub - DS USB should also work.
The DS only require VBUS for signalling (doesn’t pull high current from USB) so an active USB hub should in fact be redundant.

On a second thought;
The DS won’t turn up in Roon as an endpoint because the RAAT is part of Bridge II.
Try another control point app.
If you intend to try a Windows computer, remember to install the DS driver.

Several users report that iPad>adapter>DS works fine: Roon 1.4 iOS 11 DS DAC plays bit-perfect PCM, DSD128 (DoP), DXD

RAAT is also part of the Roon endpoint support for iPad, or it would not be playing to the iPad’s internal speakers.

And here’s my thread on the Roon forum:

But isn’t this limited to Airplay?

Roon uses wifi to endpoints.

Yes, but wifi says nothing about protocol. When you select iPad as an endpoint within Roon my understanding is that Airplay transcode is used meaning that 16/44 is what you get at best. Your iPad cannot play all your hirez files natively.

My understanding is that Roon endpoints are WI-FI. Either an Apple phone or an IPad Pro in my case. My music is served to my Bridge II over Ethernet from a Roon core on my NAS and as such doesn’t have a bandwidth issue. Or am I missing in the response?

Read the related threads. Roon endpoint on the iPad offers up to 384k and 32-bit.

Ok, so I guess this means that Roon server sends to Roon app on Pad containing RAAT that again transcodes the media to a compatible format for play on iPad?

I will check the Roon link.

Exactly. Here’s the Roon app downloads page.
For iOS, the app is a Control point and an Output.

Making it work with the DSD is that part I’m having trouble with…

I doubt that iOS knows how to output a native DSD stream. It is built on the USB Audio Device Class 2.0 spec, which only deals with PCM streams. But Roon should be able to support DoP for DSD64 and maybe even DSD128 audio data, output via USB to a DAC which can cope with that.

Please use the search function before making unsupported assertions:

Which assertion was that comment directed towards?