Airplay & downsampling

Ipad2 can also stream hi-res files from a DLNA server. I am using PS Audio's ELyric app on the ipad to stream from Logitech Media Server (with the DLNA add-on) running on my iMac. The CCK feeds USB audio to a Nuforce uDac2.

My earlier comment on FLAC files was a reference to files transcoded from FLAC to ALAC and residing on my iMac. They play fine with the eLyric player but not with iTunes running on the pad.

I suspect the limitation is on Apple TV/AE where the DAC is limited to 16/44. Big question is whether other units/airplay devices have better DACs. Zeppelin had a 24/96 DAC, but I don't know about Zeppelin Air.

Apple is stuck in 16/44 world for te time being, maybe because it wont make money from the masses by bringing in HD music. As we know, Jobs was working on it but he's gone now.

Can't see any reason iTunes wouldn't stream 24/96 (bandwidth permitting). It would be streaming a file which is converted to analogue by the DAC? Question is, what can the DAC handle?

Found an excellent blog post on this topic:

http://amiexp.blogspot.com/2011/11/airplay-to-airport-express-with-2496.html

iTunes (and presumably iPhone, iPad etc.) seems to be the bottleneck as it always converts to 16/44 when outputting via AirPlay, even to Apple TV, which is capable of 16/48. This means that 16/48 content will be converted not once, but twice, losing quality in the process.

I suspect that many of these issues could be addressed via software, but Apple has shown little interest in the HD audio maket to date, presumably because they don't yet sell HD content via the iTunes Store.

For streaming audio output, I'd recommend AirPort Extreme over ATV, since at least this does bit-perfect digital output of 16/44 files. Seems like this is the best quality currently available via AirPlay unless you ditch iTunes. Anyone know of any third-party software that does a better job?

Thanks Keith, interesting blog.

When using Pure Music as a music server, you set Audio Mini at 24/96. I've just read that in iTunes

This is encouraging as we're then left to the end device. I have, however, read so much conflicting information now. B&W Zeppelin plays 24/96 but I've read that it's only via USB. Not sure why Apple would restrict it.mmmm So close and yet...

Interesting. That suggests that changing the Audio MIDI setting could be used to adjust the behaviour of iTunes.

The Audio MIDI Setup application does indeed have settings for audio output resolution, which by default are set to 24/44, but go up to 24/96. However, this is labelled 'Built-in Output', so it seems doubtful that it would affect AirPlay quality. If what you say is correct though, it might be worth experimenting.

I'm wondering the same thing; odd that nobody has a definitive answer.

In my case in a nutshell: does changing the Audio setup's Internal Speakers setting (whose output is sent to an Airport Express via AirFoil) to 96K ensure I get that via my 3.5 mm jack to Y-split RCAs at my stereo?

TIA!

The DAC in the Airport Express is limited to 44.1k so you wont get 96 in your stereo. 16/44.1 is pretty good though at the end of the day, but no cigars (yet). Mastered by iTunes sound good on my hi-fi (get upsampled though).

Thanks, Martin!

That's unambiguously documented, is it?

When I get my own DAC and pull from AE that way, will I lose then?

Appreciated :-)

I'm 99 % sure the AE is limited. Question is what does Airplay stream. I'm a bit dead ended here. Seems like a fairly simple question doesn't it. I'll keep digging...

What you need is a DAC which tells you what the input is. I don't have one of those but they are around. You need to borrow one of a friend.

Digging.

I think the answer here is pretty well explained and documented in the post above from Keith Wilson. I have also heard it from 3rd party manufacturers: AE and ATV are hardware limited to 48/16 so Airplay converts everything to that format. If you want to stream hi res files in their native form you must use a different streamer.

Thanks, Vin and Martin; I've looked extensively but never found incontrovertible 'proof' that AE downsamples for non-AirpLay networking.

In fact I don't want to stream as such - just to send FLAC files via AirFoil from VLC. And eventually using a DAC.

Thanks!

Thanks for the concise troubleshooting everyone. This is extremely helpful and may surprise many audiophiles that apple who takes great pains to deeply integrate the core audio service into their OS is dumbing down the audio stream with their airplay devices. I fear Apple may be headed down a different road these days. You know the one, smoke and mirrors/misinformed customers allowing Monster Cables to sell garbage products like Beats by Dre at an astronomical markup while being sought after by the masses.

Having read this I may do some listening tests this evening between an airplay stream and my macbook pro directly connected via tosslink out it's 3.5mm/optical combo jack and report back.

Just heard from RogueAmoeba definitively that Airfoil transmits audio to your remote devices based on the AirPlay audio protocol, which specifies a 16-bit stereo Apple Lossless stream at 44.1 kHz.

Which answers that.

Thank Mark, nearly but no cigar!

I have to say that 16/44.1 sounds very good anyway but...

Another couple of years then I guess.

See you then!

Martin, Yes - we now know for sure that AirPlay downsamples.

You must be right - it can't be long before Apple introduce better rates.

But would that mean new hardware to take advantage of it, ie a new AE?