Sorry…I stopped using anything but HDMI so long ago (because of hi-res audio formats) that I didn’t even think about limiting to S/PDIF. It has so many limitations that I figured a full-blown audiophile would still use HDMI to output to a high-quality outboard DAC.
I didn’t realized that HDMI was a fully packet-based system, as @grahamh said. In that case, jitter wouldn’t be a factor even with PCM. So, one more win for HDMI.
As for FLAC over HDMI, it’s definitely not in the spec, but some AVRs do seem to support it, based on Google results.
Actually reaching the limits of my knowledge, but packetised may be the wrong word. I think the audio track is sent during blanking, so not a continuous stream. Not subject to jitter as such but the sender and receiver are going to be doing things to sync the audio to the video. Therefore the potential for non-audiophile performance is there.
I suspect the best performance would come from a good quality USB DAC.
That’s right… The limitation of HDMI is that audio is not synced with focus on perfect timing, but with focus on sync to the video stream. The audio stream is not the priority with HDMI, but the video stream. What I read very often is that audiophiles don’t like that. I don’t know, if this limitation is audible
But as there’s no alternative for multichannel lossless audio, not even with USB, there’s not much of a point in discussing the limitations of the only option
And note that if you are worried about timing issues with HDMI, you should be just as worried about USB, as it definitely is packetized between the host and the device.
Personally, I think (and most double-blind tests agree) that the jitter issue is completely overblown. But, any AVR/DAC that in any way buffers the input and re-clocks the output will not have any cable-induced jitter. Technically, it would be as accurate as you can get, short of storing the PCM audio and the DAC on the same chunk of silicon. And, as long as the delay caused by the buffering is less than a video frame, you’ll never know the difference. Don’t get me started on people who think that multi-channel audio requires a separate DAC per channel because otherwise the channel timing is off. Those same people don’t keep their speaker placement accurate to 1/10th of an inch, which throws off timing by more than single-DAC delays on 8 channel audio.
One last thing…all of the lossless compressed formats have some form of checksum, so they do have an advantage that the decoder (which can be right next to the DAC) can at least identify some errors in the stream that were caused by cables. Raw PCM does not have this advantage. So, overall, I think your best bet for max audio quality is to send a lossless compressed format across the wire to your decoder/DAC.
Yup, you’re right… If you have a lossless audio data stream (Dolby or DTS), this is always better. The problem is that e.g. surround FLAC files can’t be converted to those formats on the fly.
But anyway: My point from the beginning should’ve been that HDMI on Vero 4k is the way to go for me when playing back any lossless audio, especially surround audio.
For stereo music I mostly use my AVR which plays back stereo music files internally. That would probably circumvent all of the above issues. There should be a direct path from the internal music player to the AVR’s DACs.
