Lossless Hi-res thru Apple Products

… I understand the Apple TV 4K is capable of producing 24-bit 96-128khz sampled lossless thru Apple Music streaming service …

It is not. The Apple TV 4K box will output all audio at 48 kHz. That is a design choice that no app can bypass.

About lossless audio in Apple Music - Apple Support

“Apple TV 4K currently doesn’t support Hi-Res Lossless (sample rates greater than 48 kHz).”

My question is, is it possible to play back local hi-res lossless audio files hosted from iTunes on my 2017 MacBook Pro sans wires, over a network, either thru the Apple TV itself …

Home Sharing through the Computers app has support for lossless (ALAC in .m4a), but not high res. I would say probably more limited than the Music app, as Home Sharing doesn’t get the same level of TLC (developer time) these days.

… or directly thru the Marantz SR AVR, which has Ethernet and AirPlay 2 built-in?

I don’t think AirPlay audio supports high res.

I am not aware of receivers that can do network disk access on their own, to play music files from there.

Is Roon w/Qoboz a better alternative?

I haven’t tried those are. Do ask their Support staff if these services fit your setup and what you seek.

It seems their apps on Apple devices do not unlock high res audio beyond how Apple Music does it (‘Roon Tested’ [the service works, is easy, but not all features], not ‘Roon Ready’ [works with their highest res]).

It is suggested to use an (external) wired DAC, connected to your audio system, to get high res audio through Apple’s music services.

To play Qobuz or Apple Music through the Denon Receiver, I use Airplay - wired, not wireless.

I’m pretty sure audio AirPlay doesn’t support high res audio at this time (maxed at 16-bit 48kHz). Wired or wireless doesn’t make a difference for this. To Mac, both ethernet and Wi-Fi are the home network, with presumably more than enough bandwidth. (9.216 Mbps needed for uncompressed 24-bit 192kHz.)

So if I stream a 192 kHz track from Qobuz on my computer and send it to the Denon via wired ethernet using Airplay, does the signal get downgraded?

• To listen to songs at sample rates higher than 48 kHz on Mac computers, you still need an external DAC. Ethernet or AirPlay is no substitute for that. For computers, the DAC solution would probably use USB. Not all DACs do 192 kHz (e.g. 96 kHz max), so watch for that specification when shopping.
• Downsampling can be seen as downgrading. Something is simplified in the conversion. Whether that is audible is a discussion for another time.
• Mac →[USB]→ DAC →[probably 2× RCA or 2× XLR]→ receiver This may give a distance challenge, as many users will not have their Mac next to the receiver.

About lossless audio in Apple Music - Apple Support

Play high sample rate audio on your Mac - Apple Support

Use AirPlay to stream audio - Apple Support (pointing out that it has no mention of lossless or high res)

I have a similar question. I'm setting up a Denon DRA-900H Network Stereo Receiver. Speakers are a pair of floor standing KEFs. My house is wired for ethernet, so the receiver is wired ethernet connected, as is my iMac. With the wired ethernet iMac I can listen to hi-res ( sampling rate > 44.1kHz) on headphones with my THX Onyx DAC. To play Qobuz or Apple Music through the Denon Receiver, I use Airplay - wired, not wireless. So if I stream a 192 kHz track from Qobuz on my computer and send it to the Denon via wired ethernet using Airplay, does the signal get downgraded (not the right technical term, be nice...)?

From my experience the Mac does not automatically adjust the sample rate for the lossless/high-res lossless from Apple Music. I have to go to the "Audio Midi Setup" utility to adjust the sample rate for my external DAC that my Mac is connected to. Which can be a hassle if a playlist has songs with different sample rates.

What I usually do instead is use my iPad with an adapter to connect to my external DAC that is connected to my Yamaha receiver. The nice thing about the iPad is that it will automatically adjust the sample rates from Apple Music directly. Unlike the Mac, I don't have to hassle with any other utility or app to adjust sample rates.

I also can listen to Apple Music with the same iPad setup with headphones connected directly to the DAC