Roon Ready is all about digital towards analog. That is Roon digital over network to a Roon Ready device.
Roon Ready Relay is all about analog towards Roon. That is, analog in, convert to digital, send to Roon and from there go to any endpoint, combine zones, etc.
Hope that helps. Look forward to whatever devices may support this and I can’t echo @Wade_Oram 's comment any louder…
I like Roon because I can build my own stuff… I’d like to build my own relay. I’ve already got ADCs, thanks.
That may be a use case I guess, but then the whole point of roon is its interface is it not?
I’m envisioning Apple Music feeding Roon just like Tidal and Qobuz, but coming from the new Roon black box being fed by an iPhone or iPad.
Yupp, and add to that, this is an opportunity to play a vinyl LP at home and stream it to Roon ARC/CarPlay while cruising! 
And then we come back to the automation control for “please extract album X from my shelves, put it on the record deck and start it playing” using voice control from ARC 
It’s a major feature if you want to dust off an old tape deck of otherwise unavailable material, likewise with vinyl, then play it to an endpoint, speakers or headphones, applying DSP if desired, it’s something some people would welcome.
Then there’s multi room.
Then there’s sources that the native Roon doesn’t support.
We’ll have to see what options the relay can have but I hope it’s DIY possible with RPI etc.
Commercial offerings I expect too, I just hope they’re not priced too high.
You can’t do that legally hijack the stream I am afraid nor is it what this is about from reading. This is sending an audio signal from one device into another and digitally route it via Roon. You would still need to use the Apple app to play music. It will be similar to the extensions that already offer this, how Wiim, Blusound and Sonos work already. This will likey be more slick than the extensions and with Harmans hardware likey a dedicated Roon box as well have SDK options for preamps to route their signals into Roon as well.
Blusound already have a dedicated hub for this so I see this as what they will aim at first and perhaps offer diy solution like Rock and Bridge for those with kit capable of capturing audio all ready.
The api for routing streams into Roon has been around for some time so it’s good to see them officially start to use it. Likely the api was first step.
It sounds to me like a routing solution. Analog source → Roon Ready Relay → Roon endpoint.
Speaking of Apple Music: if the audio routing is possible even “virtually” (internal digital source, not only hardware) that could possibly open the possibility to leverage Roon Ready Relay technology to send Apple Music’s digital audio playback output to compatible Roon endpoints.
That would be possible only on a computer, though. Apple Music app → Roon Ready Relay routed virtual output → Roon DAC/streamer.
Mobile devices (smartphones/tablets) would be unfortunately excluded making it less convenient, unless a little wireless Lightning/USB C Roon Ready Relay dongle would be developed to bridge, say, an iPad/iPhone with a Roon endpoint.
We’re excited by Roon Ready Relay’s potential to extend the Roon Partner program and welcome more manufacturers to the Roon ecosystem.
??
But the option of using the iDevice/Android phone as a source for Roon is rather tempting.
Auralic is implementing some dirty hack called LightningCast to be able to stream Amazon, Deezer, Apple Music etc towards their devices, but this is still a really obscure solution.
Despite the discussed focus on analog sources, any chances to:
I’d imagine this would be against all copyright and would be a legal nightmare. Taking a digital output or analogue output from a streamer would not have same implications as your not hijacking the source. Open source can get around this stuff as it’s not a product that charges for its use as current extensions already do this, but they are not a profit making company.
Yes
Yes, absolutely. Just to visualize my thoughts, here’s a scheme:
The goal is to listen music through Roon adding more sources. That’s it. I doubt Roon users want to leverage its “ecosystem” for fishy things like pirating/copying/hijacking the audio stream, etc. It doesn’t make sense.
Audio/video transmitters already exist and are basically doing more or less the same thing. I can “rip” the entire Apple Music catalogue right now if I would. Digitally, in hi-res (if available) and lossless. Just press play on Apple Music app → Route it to an audio virtual output → Pick the virtual output as a source in an audio software and record a Flac or whatever format. It takes just time and storage.
Who is doing this? For what purpose? Sell the copies somewhere? Make an illegal archive for herself/himself for future use? Nah.
I get your point: strictly legally speaking it’s borderline. The same can be said, for example, for way bigger players like AI companies crawling right now the entire public internet to suck contents.
Actually, i was thinking along your third option, i.e. a Roon virtual output device tapping into the Rooniverse.
Start “Roon Remote 2” which enables a virtual sound output device on the smartphone/tablet and then switch to your desired source app, like Spotify, Bandcamp, Apple Music etc.
Anyways, likely not the purpose, but an interesting use case.
Roon has already “unified” all of my output devices, maybe we are looking into the “unification” of inputs and sources?
Sounds really cool… let’s say I got a roon certified dac/streamer with digital inputs and outputs, could I connect my turntable to such a streamer to use opra and DSD upsampling ?
Or will it be a workaround solution like rooextend ?
Would also be cool to get Dirac integration somehow without using a virtual workaround like blackhole etc …
That would be even more convenient. No hardware dongles involved and more future proof (who knows how long will iPhone/iPad carry a physical port in the future?).
I’m afraid that tapping the digital audio output on iOS/iPadOS to route it to a Roon Ready Relay virtual output would be tough. I guess iOS/iPadOS doesn’t allow it. Glad to be proven wrong by seeing Roon making it possible.
I see a business opportunity: Trained monkeys to play and flip the vinyl. 
Will Roon identify the analog source and display TiVo information? What are relay devices? I admit I still don’t get it.
It’s theoretically possible because Shazaam can. However, I doubt it and expect it to take the stream for multiroom and DSP.