Hi-Res Lossless Audio via lightning port

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Hi-Res Lossless Audio via lightning port

Hi community members,

Currently, I have a Yamaha AV receiver (RX-V677) which is an Apple MFi certified device as it has the “Made for iPod/iPad/iPhone” certification symbol.

I am able to connect my iPad Air 3rd Generataion (running iOS 17.0.2) to the RX-V677 via the supplied lightning to USB-A cable. The RX-V677 is then able to access and play music from my playlist and albums in Apple Music. In addition, audio from games, AppleTV, Youtube, Youtube Music, other streaming apps is also sent to the RX-V677. I can also control playback functions like stop/pause/skip/next or previous track using the RX-V677 remote.

The quality of the audio is fantastic but I am not sure if the audio being sent through to the RX-V677 receiver is lossless or Hi-Res lossless. When I check the input format of the audio being set through the USB, the RX-V677 says it is “Digital” and 2 channel and nothing more. The RX-V677 also supports AirPlay and when I stream lossless audio via AirPlay, the input description also states "Digital" and 2 channel.

When I play a Hi-Res lossless music in the Apple Music app, I do see the Lossless or Hi-Res Lossless indicator. So I know that the iPad has downloaded or is streaming the Hi-Res lossless audio.

I am also aware that the RX-V677 supports FLAC/WAV up to 24bits/192khz and ALAC up to 24bits/96khz.

As some of the music I play are in Hi-Res lossless 24bits/192khz ALAC, the RX-V677 still happily plays the audio although 96khz is the limit for ALAC files.

So my thinking is that the interface that connects the iPad to the RX-V677 is using PCM/WAV streaming audio packets rather than sending the ALAC file contents through to be played. Or that the interface downgrades the Hi-Res lossless audio 24/192 stream to something like 24bits/96khz or 16/44.1khz.

Can anyone confirm what audio format is being streamed or sent using this type of wired connection?

thank you for your time,

Norman.

iPad Air (3rd generation)

Posted on Oct 2, 2023 5:10 PM

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Answer 1

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Norman Soh Author

Level 1

6 points

Oct 30, 2023 4:07 PM in response to Norman Soh

Hi all,

I have done quite a bit of research on this topic and I think I have found a definitive answer to my own question.

According to the MFi Accessory Interface Specifications for Apple Devices R2 spec, the USB Host mode audio requirements are:

16-bit LPCM

44.1 / 48 khz sampling rates

Ref: https://www.scribd.com/document/325596037/MFi-Accessory-Interface-Specification-for-Apple-Devices-R2

So it would appear Apple Music / Youtube Music Premium audio is streamed to my Yamaha RX-V677 is at most 16bit 44.1/48Khz (CD quality) via the USB "Dock Connector". So the Apple audio subsystem would be decoding ALAC or AAC audio files and converting to a 16bit 44.1/48khz LPCM stream.

So although the audio sounds great at CD quality, it is by no means Hi-Res (24bit 96/192khz) quality.

BTW, I also found information about a DAC that supports iPod/iPhone/iPad devices and the information about the audio streaming specifications is located here: http://www.ratocsystems.com/english/audio/dl/pdf/ral_keb02ip_iPodlegacymode_users_manual_1r10.pdf

I hope this helps others with old equipment that had "Made for iPod/iPhone/iPad" certification.

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Answer 2

Jan 9, 2024 9:16 AM in response to Norman Soh

Thanks for doing this research. Pathetic that Apple has not replied.

Im in the same boat and have two Yamaha receivers in different rooms. I was looking to upgrade from the AirPlay.

Would it make a difference to use lightning to coaxial or lightning to RCA instead of lightning to USB-A?

It is frustrating that the signal info on the receiver does not provide anything while connected to Apple devices.

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Answer 3

Norman Soh Author

Level 1

6 points

Jan 28, 2024 4:14 PM in response to GolgiBody36

I don't know how the sound quality would be if you used a lightning to coax/RCA cable.. I would assume that a lightning to RCA cable would have a DAC inbuilt into the cable.. So the sound conversion quality from digital to analogue would depend very much on the DAC itself. That is my thinking - but I may be wrong.

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Hi-Res Lossless Audio via lightning port

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