yep…BTW using that Hifiberry Hat https://www.hifiberry.com/docs/hardware/comparison-of-hifiberry-cards-for-audio-recording/ was inspired by you. Need to admit that 
Works great with NAA also when using RopieeeXl. So those HAT Input are additional hardware based methods…, + Advantage of using Airplay 1 (via Software or Hardware - both same result) as input is, that you route any audiosignal from your iDevice toHQPlayer in ALAC 44.1/16. I like this very much. Depending on your source it is lossless or it is upsampled by Airplay I. Advantage…any source 
You just switch Apps at iDevice while having iOS System Out at Airplay 1 endpoint. Super super comfortable not cables, CCC, etc…Feeding afterwards HQP by the several “methods” described here is possible of course. I even (digital) feed my Sonos stuff upsampled from Jussi (favorite Sinc-Mx right now 
). Of course you could use Convolution engine and Matrix with your Sonos stuff too, if you want too…lol… For my fun chain this is really great. If you stream via Airplay 1 e.g from iOS Tidal App (in 44.1/16) or from Qobuz App (in 44.1/16) is is much more than fun only! And you can still use their original iOS Apps! Myself loving to watch videos with iOS Youtube Music App too. But if you upsample videos too hard, you get delay between sound and video of course. And yes, I watch on my iDevices regular TV and movies too with that in spatial sound too. This all works!..Again and again and one more again, this works per (free or donationware) Software only too! Maybe even better SQ per Software instead of hardware as >>no additional hardware box with additional challenges for jitter, delays, unneeded usb interfaces, power supply units,…etc… in the signal path. lol @hammer So, if you can live with ALAC 44.1/16: software is the superior way imo. Clearly! Much less expensive too…++ For serious listening using Roon to HQP to NAA. Using Qobuz prefered as natively supported by Jussi himself or Roon. At lot of Michael´s challenges arise here because he uses Apple Music, which is not supported by now by e.g. Roon or any other. Same with Amazon Ultra. Guess this folks (Apple and Amazon) simply do not want that…Awaiting for Spotify Hifi just the same restrictions…Ok…So, taking the stream from Sonos as digital output allows me as couch potatoe to use my touchy iDevice for switching and not having to run to the Mac… Thank you + If your are really up to, you can feed >>any source in FLAC 96 to Roon too by using Roon´s Radio feature. Once in Roon you can output to HQP of course. Take a look here for this way, e.g. via Icecast or simmiliar: Can a local server stream FLAC to Roon? ++ If you are not in the Apple universe you can build this all on Windows or Linux or Android too, it is always the same principles…In a nutshell there are plenty of options, be it hardware or software!
PS You may build similliar with google cast audio in 96/24. But myself dropped google cast meanwhile as it seems to me, hires audio not beeing really be supported by google anymore. 
PPS And let´s wait on this too. Matter could bring universal casting for TVs and video players - The Verge
++Edit; final edit on this done too…I think, if someone is really interested in this topic, he or she will find in this thread an excellent source. But it requires to critically read and challenge too what some folks claiming here! e.g. one of those hilites here “Since 99% of all music is base rate 44.1k…” Ok, ok, no offense please…