As I am still waiting for my Technics integrated amp to arrive from the service center, I am getting impatient and wanted to try Roon with the following:
Mac mini as core → USB → EarMen Sparrow headphone DAC → Aeon 2 headphones
And then use iPad or iPhone also as endpoints.
Mac mini connected to my network through Ethernet.
Does this work or am I nuts?
Why would you think that wouldn’t work?
This should work just fine
Because it’s just a headphone DAC; so it can only be plugged on the other end to my headphones. If so, how can Roon spread its DAC-ized sound signal to other endpoints?
Over the network or thru a USB hub.
As the signal path can’t utilise the Sparrow DAC for anything other that the headphones connected to it, other endpoints will be reliant on whatever Roon does to support the signal processing through software.
Err… what do you mean by ‘work’?
See my follow-up question above - is it sufficient to simply plug it into the mini’s USB (without having to plug my headphones on the Sparrow’s other end) for its high quality DAC-ized stream to be used by any endpoints in the house?
For other Roon end-points, you would need additional DAC’s connected to your Roon core by ethernet or USB. For each of those DAC’s, you need a Roon ready or Roon tested device that would be connected by ethernet to your network, then USB, HDMI, RCA, etc to your sound system or active speakers.
For now, my intended use would be very simple, Jim:
When wearing headphones:
When playing through my iDevice:
What do you mean by this? Roon sends a digital bitstream to recognizable endpoints which each must have its own DAC. Roon doesn’t send analogue signals…
I thought iPhones could be endpoints through Wi-Fi. So they can’t?
That’s possible because the iPad and iPhone are endpoints with their own DAC. They are enabled as private endpoints, so can only be configured from their respective Roon Remote app.
You can do this. Your Roon core (Mac Mini) will send the music back to your router by ethernet, then to your iPad or iPhone by WIFI. Your iPad and iPhone can act as both a Roon control device and a Roon end-point.
Yes this is possible. The iPad and the iPhone can be an endpoint. Music is played through the built in speaker, or through a paired headphone.
As long as the wireless of the iDevices is the same network as the Mac mini.
Tks - that’s a relief, to some extent. But I guess in this case they don’t benefit from native MQA decoding from either the Sparrow or (when it arrives) my Technics amp, then?
P.S.: Saw Jim’s and Peter’s replies now; so is native MQA supported in that scenario?
P.S. 2: Yes, wi-fi is in the same network.
Neither iPhone nor iMac have any MQA capabilities… But this may change if and when Meridian buys out Apple… 
Your Roon core can do the first unfold of MQA files. If you want full MQA rendering, you need an MQA DAC. For instance, an AudioQuest Dragonfly plugged into your iPhone or iPad feeding your headphones. If you go this route, you also need an Apple camera adapter between the iPhone and Dragonfly DAC. You can find the Dragonfly and camera adapter on Amazon. Get the adapter that allows you to plug in your charger at the same time.
EDIT: If your Sparrow can do this, forget the Dragonfly.
I see your Sparrow is a MQA renderer… you do the ‘first unfold’ with Roon and let the Sparrow do the rendering… So that’s ok for your headphones listening.
Roon can work as core decoder. So you have the important first unfold. You do not get the 2nd unfold of MQA, but if you don’t have the frequencies above 48 kHz is not really relevant in this situation.
On the iDevices.