I currently connect my second headphone Roon set-up using iPhone/Lightning USB Adapter/Dragonfly Red DAC/Amp/Headphones. The iPhone is reongnized by Roon as a Zone and I stream from a Fidelizer Nimitra S Computer Audio Server as Roon Core.
I am swapping the Dragonfly for an external Schiit Modi 2 Uber DAC and Aune X7S headphone amp.
A few questions:
(1) Which connection below is better?
(2) Will iPhone still serve as Roon Remote in both cases? It was suggested I may need Roon Bridge, but I’m not sure how that would work.
Home 2a: Tidal/Roon
iPhone 7 > Lightning to USB Adapter > USB A to A/male to male cable > Sabrent Powered USB Hub > USB A to B/male to male cable > Schiit Modi 2 Uber DAC > RCA ICs > Aune X7S headphone amp > WW Red 4 pin XLR headphone cable > HD800 headphones
Home 2b: Tidal/Roon
Google CCA > Min-Toslink/Toslink Cable > Schiit Modi 2 Uber DAC > RCA ICs > Aune X7S headphone amp > WW Red 4 pin XLR headphone cable > HD800 headphones
iPhone is Roon Remote in both cases.
My personal experience is that for stability, the Chromecast output is better. In general, folks will tell you that the jitter you get with the optical out from the Chromecast make for a detrimental audio experience, but I would take the tradeoff (if any) for a more stable listening experience. I have never been able to get my (albeit Android) phones, ie top level Samsung devices, to play consistently as end points. Chromecast on the other hand, has been rock solid with Roon. At the end of the day, let your ears decide, if both are streaming consistently, and if the IOS end point solution is a bit iffy, then take that into consideration 
PS… As a permanent endpoint I am now using CCA-Toslink-Chord Mojo-Beyerdynamic T1’s or Adam A5X speakers, in preference over a USB connection to my Ethernet wired laptop endpoint; I can’t hear difference between the 2 and it’s just so convenient to be able to unplug the laptop on a whim without upsetting the music
In your case, you can factor in the issue of using the Iphone as end-point and remote, far more convenient to have the remote without wires dangling.
Hope it helps.
Remarkable for a $35 device. Do you find that aftermarket Toslink cable is worth the cost? Not so much a question about the efficacy of upmarket cables (of which I am a proponenent), but rather the idea of spending $150 to make a connection from the $35 CCA.
BTW, I was a confirmvd Samsung/Android user for many years. I finally switched to iPhone because I cound not get a stable connection with Bubble UPnP/Tidal to my Samsung. Things may have changed, but your Android instability concerns ring true for me.
IThanks for your help.
I don’t personally find the cables give different sound. But that’s just me 
- some people can hear differences if they coils cables in different ways or route them differently through the house. That’s a rabbit hole I just don’t want to go down, lol.
I usually find a good solution and stick to it.
Digressing; I got a pair of Ik Multimedia Iloud speakers the other week. I am running them off my mojo now via the toslink. They are, bar none, the best ever purchase I’ve made speakerwise. They defy physics in the depth and solidity of the bass and clarity throughout the frequency range. They weigh next to nothing, are the size of a couple of large cans of soup, and look like a pair of crappy throw away speakers, but by golly they sound on par with my A5X’s. I kid you not. I had them sitting on top of them in the front room this afternoon and was doing some A/B listening. Jaw was firmly on the floor. Of course, they’re not quite able to handle the maximum dynamics like a 100wpc speaker can, these are 25wpc, but within limits they rock!
