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TV optical out vs NAD M12 digital preamp

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Dec 19, 2020
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#1
I currently use apple tv for television and music. My apple tv connects to the TV's hdmi port. I then use the TV's optical out to connect to a Topping E30 and the Topping connects to my amplifier.

I would like to get some opinions regarding the improvement, or not, of sound quality if I avoid the TV and purchase an NAD M12 digital preamp (with optional HDMI card) which will allow me to split my audio and video coming from my apple tv. By doing this, I no longer route audio through my TV.

Am I likely to improve the sound quality by bypassing the TV for audio and purchasing the NAD M12 digital preamp?
 

Vasr

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#3
Sorry dude, for your 2-ch setup, the best excuse you can give the missus to plunk down $4k on the eye candy you have been drooling over is that you can leave the TV off while listening to music since most TVs won't pass through audio on standby/off. But I don't think she is gonna go for it.

And don't even try saying that you can go over the TV sampling rate limitation of 48khz if you had the M12. You might even lose visitation rights that way.
 
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Thread Starter #4
Sorry dude, for your 2-ch setup, the best excuse you can give the missus to plunk down $4k on the eye candy you have been drooling over is that you can leave the TV off while listening to music since most TVs won't pass through audio on standby/off. But I don't think she is gonna go for it.

And don't even try saying that you can go over the TV sampling rate limitation of 48khz if you had the M12. You might even lose visitation rights that way.

So no difference between 1) the TV doing the separating video/audio and then converting to optical signal and then Topping converting to analog or 2) the NAD doing the separating of audio/video and converting to analog? First, there is one less step (no conversion to optical) and second one has to wonder just how good the TV is at doing all the things it needs to do.
 
OP
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Thread Starter #5
No it will be practically the same, unless the TV is resampling the music.

Does the E30 have a screen?
The TV is not resampling, but the TV route includes one additional step (the conversion to optical). The E30 is the DAC. It has an information screen which tells which rate its running.
 

Vasr

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#6
So no difference between 1) the TV doing the separating video/audio and then converting to optical signal and then Topping converting to analog or 2) the NAD doing the separating of audio/video and converting to analog? First, there is one less step (no conversion to optical) and second one has to wonder just how good the TV is at doing all the things it needs to do.
Conversion to optical from digital audio via HDMI is just shoving the same digits bits in general (with some minor exceptions). There might be some second order effects like more jitter but typically has no audible impact.

Most TVs limit the optical out to 48khz sample rate but they also typically indicate that they can only do up to 48khz to the upstream HDMI source, so at most some TVs might up-sample 44.1khz received to 48khz before sending out via optical. This would have no audible impact in practice.

For TV shows with Dolby/DTS encoded 5.1, you can in theory send the encoded stream via HDMI from Apple TV bit-streamed over two channels. Your DAC cannot handle these passed through optical so you will have to specify 2-ch PCM and let the TV downmix. But most likely the Apple TV audio out mode has been set to Stereo and Apple TV will be doing the decoding and down-mixing which is what you will have to do going through the M12 anyway. So, no difference.

TV is just acting like a $40 HDMI extractor to get digital 2-ch out. If you get the NAD M12 you will be buying a $4000 HDMI extractor for this use case with no audible benefits even if you are able to play music with higher sampling rates in the latter if Apple TV can provide it.
 
OP
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Thread Starter #7
Conversion to optical from digital audio via HDMI is just shoving the same digits bits in general (with some minor exceptions). There might be some second order effects like more jitter but typically has no audible impact.

Most TVs limit the optical out to 48khz sample rate but they also typically indicate that they can only do up to 48khz to the upstream HDMI source, so at most some TVs might up-sample 44.1khz received to 48khz before sending out via optical. This would have no audible impact in practice.

For TV shows with Dolby/DTS encoded 5.1, you can in theory send the encoded stream via HDMI from Apple TV bit-streamed over two channels. Your DAC cannot handle these passed through optical so you will have to specify 2-ch PCM and let the TV downmix. But most likely the Apple TV audio out mode has been set to Stereo and Apple TV will be doing the decoding and down-mixing which is what you will have to do going through the M12 anyway. So, no difference.

TV is just acting like a $40 HDMI extractor to get digital 2-ch out. If you get the NAD M12 you will be buying a $4000 HDMI extractor for this use case with no audible benefits even if you are able to play music with higher sampling rates in the latter if Apple TV can provide it.
Wow, very helpful. Thanks for your time.
 
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