HDMI vs optical vs streaming > Spotify

Hello
I have an Atom. I connect my samsung TV by HDMI.
Questions: Is HDMI digital or analog? since if it were analog it would be wasting the DAC of the Atom.
Do I get better sound quality through HDMI or Optical or are they the same?
If I use Spotify from my TV (to see the info on the big screen) via digital connection: would it be the same sound quality as running Spotify directly from the atom? or not?
I have the feeling that the sound quality drops from the TV, but I do not know if it is suggestion
Thank you

Both HDMI and the fibre optic/TOSLINK are digital connections.

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I am assuming the TV is smart and acting as a Spotify Streamer. You might get better results with a better streamer of course. Does the TV see the Atom on the network?

Yes, it is a smart TV. It includes the spotifiy app and can work as a streamer. It also recognizes the Atom on the network.
You say that the Atom is a better streamer, that is, better audio quality?
That is what I do not understand: if despite being digital, if it does not go through the TV DAC, the quality is less than or equal to the Atom streamer.
Thanks

Yes, you would expect the same digital input to sound the same…

There could be slight differences though. I.e. my TV (not that smart, from 2011) sends a fixed 48kHz signal, while most standard music is encoded with 44 kHz (=CD). So, if you decode it on the TV and send it via the connection, it might have to be „converted“, which might loose quality. (Not sure, if this happens on your side.)
Again, if the TV decodes the stream, it’s responsible for buffering etc., while the Atom will kind of play the HDMI (or SPDIF) signal in „real time“. This could make the playback subject to jitter/timing on the connection from the TV. If the Atom streams itself, it can better manage the timing from it’s own buffer for streaming/decoding internally to its DAC.
In theory, the decoder itself could make a difference.

After that, we enter the general debates about effects of streamers, cables, digital transports, … on sound quality via noise floor, power supplies, …

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Does he TV show the bitrate of the stream it plays?
Does it have any EQ functions? (TVs like to adjust picture and sound on video content, not sure how it treats an audio app.)

I’m assuming that the lower the streaming bitrate, the less critical the cable is? Obviously Spotify and other services aren’t usually more than 256/320Kbps.

The Atom display indicates a speed of 48khz.
The TV equalization is disabled in the connection to the Atom (I suppose it only works in the analog treatment of the TV sound)

The connection speed indicates 48 khz. I assume here indicates sound degradation?

The signal indicates 48 khz. Should be enough
The explanation of the buffer is very useful, obviously the Atom is better prepared for that

On a slightly different note I watched a YouTube concert on my Tv with it connected to my Star via an optical lead and it sounded really good through the Star and my Neat Xplorer speakers

Depends on what Spotify shows as original rate.
(And I cannot judge, how easy this conversion would be able to hear.)

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Yes that means the internal DAC of the television is resampling the signal, which in principle may cause a bit of degradation. Whether this is audible though is a different matter!

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I think your case is different as it depends on the sound quality of that youtube video.
In my case it would be the same spotify file received directly on the Atom or received on TV and digitally passed to the Atom without prior conversion

I would have thought the optical option would sound better.
HDMI shares much more information - audio/visual and probably going through the screens processing abilities.
Optical should be audio only and processed by the Naims abilities.

In a HDMI cable the audio and video signals go through separate wires, so they won’t get mixed and only the audio wires are used on the Naim side.

In theory with HDMI ARC the original signal is relayed through, so if the TV’s Spotify app receives a 44.1Khz signal that is also what is sent via HDMI to the Naim side. This would be completely lossless.

Unfortunately there are multiple HDMI ARC variants and not all behave exactly the same. So the quality of the signal using HDMI may depend on the specific ARC implementation in the TV. Some implementations may resample the signal for various reasons.

With optical many TV’s resample incoming signals to the DVD standard of 48Khz, so it depends on the quality of the internal DAC of the TV how well the signal is processed.

The best approach is probably to try out both and subjectively decide which one you prefer…

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That’s interesting. I have an optical out from my SkyQ box. Wondering if that’s running out from the sky audio processing - set to “ normal”??

Are you running the optical signal into the Ndac? If so, you may be able to see on the display if the signal is 44.1Khz or 48Khz.

Some more advanced boxes have an ‘audio bypass’ option which should leave the original signal intact without any processing. If the SkyQ box has a ‘normal’ setting then perhaps they also have one for bypass.

I would assume a computational digital conversion of the signal for „resampling“ between rates; I very much doubt a DA-AD path exists in these devices.
(Just nitpicking. :grimacing:)

Yes right, the important part i guess is that this process is in principle not lossless, so there is a potential degradation in sound quality (in theory).

From another source:

First things first, a change from 44.1 kHz to 48 kHz is an example of sample rate conversion, not upsampling. You do not zero-pad, you calculate (interpolate) the sample values as if the signal had originally been sampled at the new rate. In the old days, conversions from 44.1 to 48, and vice-versa, were the toughest, however, we now have far more computing horse-power to do it. You will be effectively calculating all new sample points, though.

This is different to integer upsampling, where zero-values are inserted between the existing samples, and an interpolating filter determines their new value. In this case, you always have the original sample values.

Does it affect sound quality? That depends on the quality of the conversion algorithm and the precision used.

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