The Core can send RAAT to a remote Bridge over the network, and then you can plug a DAC or the AV10, whatever has a USB input, into the Bridge. It’s helpful if you need to access the DAC over the network but it’s not Roon Ready and doesn’t speak RAAT. If you plan to install the Bridge on the same machine (NAS) as the Core, you can plug the DAC into that machine anyway, why would you need a Bridge?
Yes, you’re confused 
Using the network with RAAT, you don’t need a HDMI cable connected to the AV10 and configure the QNAP as Roon endpoint.
But: If you want to hear multichannel music, then you can configure also the NAS as Roon endpoint and then you need alsa (more or less the audio drivers for linux) installed.
Check on your NAS in the console with aplay -l, if alsa tools are installed and which sound devices are available.
Otherwise search how to install alsa on your QNAP.
Let me ask you this, if an end point device (AV10) does not speak RAAT is it limited to CD quality ie Airplay when using Roon to stream to it either it be Qobuz or music from the NAS?
Yes, but only if the only way to access that endpoint is over the network, because then the only available network protocol is Airplay. (Assuming the endpoint doesn’t speak Chromecast)
If you can plug the endpoint into the Core machine by USB (or whatever other digital inputs/outputs are available), then it isn’t. And if you plan to install the Bridge on the same NAS as the Core, you need digital output on the NAS anyway, so you can skip the RAAT and hence the Bridge as there is no network involved.
If I understand your plan correctly
The AV10 does speak Chromecast. Roon see it as airplay. I guess I could try and disable airplay on the AV10 and that would force Roon to use Chromecast thus fixing my issue without messing with the NAS.
Make sense to you?
I actually looked on the AV10 specs and it mentions Airplay (2) but not Chromecast?
https://www.marantz.com/en-us/product/av-separates/av10
Roon would usually show every input that is enabled on the device. E.g. if I enable Airplay and Chromecast on my Naim, Roon shows it as Roon Ready, as Airplay and as Chromecast, and I can choose either way.
My mistake, I’ve has to unit for 4 days, still learning it. I must have been confused with another model.
I don’t know why, you need to solve that either for Bridge or for a full Core. Whatever you can do with Bridge you can do with the Core.
I might be able to hang a chromecast dongle off the AV10, but I’m not sure if that would be a bit cheesy.
I thought you said you had Ubuntu installed on the NAS. If you have Ubuntu installed, you don’t need QNAP packages, you install Ubuntu packages.
Or was that a plan that you had, to install Ubuntu on the NAS? I would recommend against that, it’s surely not straightforward at all.
If you are running QTS (the QNAP OS), this thread may help (look for the posts by Crieke)
Ubuntu Linux Station installs Ubuntu in a virtual machine on top of QTS. That doesn’t help because the Ubuntu still needs to go through QTS to access the audio hardware, so the QTS audio drivers are still necessary. From the QNAP website, my bolding:
About Ubuntu Linux Station
Ubuntu Linux Station is an Ubuntu Linux operating system installation tool for your QNAP device. Integrated with Linux containers, it helps you to easily download and install lightweight fully-virtualized Linux OS images.
My NAS Roon Core works great and I stream to a bunch of speakers in the house but I’ve lost the ability to stream Qobuz, Marantz HEOS doesn’t support currently. I use HEOS on mobile and on the AV10 as its bultin to access music server on the NAS via DLNA I suppose.
Thats why I held off installing it as I didn’t have a solid plan to make it work. You and others have helped my under I don’t need bridge since I have CORE.
So you need to make the ALSA drivers in QTS work either way. The thread that I posted above is the best I can find on the forum. And this post seems to suggest that with current QTS this should simply work:
You did click the Enable buttons here?
Yea I have but I don’t know what they are doing. I thought it would enable the HDMI port on the NAS that was connected to the AV10 but when QNAP told me no audio out of those I gave up on that plan.
So, you’vr alsa installed and what is aplay -l showing, when you’ve connected thr HDMI cable to your AV10?
On my QNAP I’ve to activate HDMI1 as sound device in Roon.
I’m not sure where aplay -l is run from? Never seen it before.
Also maybe I could try this and leave the NAS alone
https://support.marantz.com/app/answers/detail/a_id/4570/~/setup-procedure-to-cast-spotify%2Cnapster%2C-pandora%2C-and-other-supported-services
Main thing I want is hires using Roon to get Qobuz to the AV10 and if I can connect via chromecast that would be sample-wise better the airplay.