Airplay music streaming and internal DAC bypass

Max_Ram wrote:

You're right, but theroretically best audio quality is reached when none but the hi-end DAC touches the digital source, an Apple TV upsample is not welcome.

I know what you are trying to achieve, this has been discussed previously and I have always maintained the upsample to 48 kHz by AppleTV 2 and 3 is not welcome but the vast majority of people unfortunately would not care or notice.

Apple TV can handle 24 bit files. You can limit the output to 16 bit in HDMI setup option.

Can you try to play a 256kbps 44.1 kHz in Computer>Music and see if the upscale takes place? Are you sure that is not your Aplifier that makes the upsample?

Yes it can 'handle' 24 bit depth files but it really isn't clear if it receives 24 bits or 16 from iTunes or not, and if it gets 24 bits does it reprocess to 16 bits for output.

I am not at this stage convinced it outputs 24 bit depth audio at all. Unfortunately neither my amp nor your DAC indicate this.

The only options for audio output I see now are Auto or 16 bit - this menu used to offer 16 or 12 bits, so without being able to select 24 bit I have my doubts and someone with an amp that clearly displays the input signal characteristics should be able to clarify.

I'm certain it's not the amp that upsamples - there have been several prior threads about this.

Alley_Cat wrote:

I'm certain it's not the amp that upsamples - there have been several prior threads about this.

https://discussions.apple.com/search.jspa?facet=content&type=discussion&sort=rel evanceDesc&showAnsweredFirst=true&q=48%2…

Some examples in that search.

Max_Ram wrote:

I've just read. So there isn't any way to force the Apple TV to output through Toslink an original untouched digital signal, it resamples everything at 16 48kHz, am I right?

That is my understanding - I'd like someone to clarify the 16/24 bit question though.

Max_Ram wrote:

I use also iTunes Match which plays original 16 bit 256kbps 44.1 kHz songs, does it resample also those files?

Yes, but I'd be less excited about it altering lossy AAC (or MP3 files if you have an in iTunes) files than lossless audio.

Max_Ram wrote:

I was wondering if the option ON in Dolby Digital (On/Off/Auto) forces some way the Apple TV 3 to output an untouched signal...did you try it?

Shouldn't affect stereo audio output at all - AppleTV decodes lossy or lossless audio files then upsamples to 48 kHz for output but as linear PCM. Stereo audio is not output as Dolby Digital 5.1 at all.

The Dolby Digital setting is useful if you use optical out.

When set to Auto, the AppleTV decides via HDMI negotiation if the output device can decode and playback Dolby Digital or not - some TVs won't so if you have AppleTV hooked up to such a TV via HDMI but are hoping to play the 5.1 soundtrack over optical Auto will fail and only provide the stereo audio track over HDMI and optical. If you set it to On and the TV can't handle DD you get no audio via the TV (assuming there is a DD surround track). Set it to Off and you always get stereo (or nothing if no stereo track) over HDMI and optical.

very interesting topic, I read through some forums etc. and fiddled around with different configs as i'm also worried that some shortcuts are taken by airplay: not only digital to analog and back but also compression while sending via BT/Wifi. My best solution at the moment is to use an iPad instead of an appleTV so you use the DAC of the iPad and the ipad is wired via analogue cable to the hifi. Actually I remember reading that iPhone/ipad DAC is quite impressive. at first you might think it's not because you listen via phone speakers or little headphones but if you think about it the iPhone is powered by nice clean direct current from it's own battery as opposed to the one in your stack whose output quality might be compromised by alternate current, ground, fan... Finally, you can also use the iPad remotely with spotify for example you can set the quality level to 4 (Extreme) on the iPad and then operate the spotify on the iPad from a macbook or iPhone.

Let me know what you think but this way at least i'm sure that high quality clean audio gets out of my iPad and straight into the amp