iPhone and iPad capabilities with and without attached DAC


(Steven Goff) #1

I’ve become curious regarding the audio capabilities of iPhones and iPads as Roon endpoints, and Release 1.5 has increased my curiosity. I’m mostly interested in using them for headphone listening, and have various question about how they work in that capacity.

First, if I drive my headphones directly from the headphone jack of my iPad Pro, for example, what sort of signal is sent to the iPad. Is it lossless PCM? What is the maximum bit depth and sampling rate that can be sent to the iPad for conversion by its internal DAC? Does Roon’s new ability to uncompress/unfold an MQA files affect the answers to these question. Is any sort of upsampling possible?

Second, if I connect a DAC to the device using something like the Apple camera connector, what sort of signal is sent through the iPad to the DAC? What is the maximum bit depth and sampling rate? When playing an MQA file, will Roon unfold the file and send 88.2 kHz or 96 kHz to the DAC? Will it send a DAC renderer the information necessary to perform further MQA upsampling?

I’ll likely soon buy a DAC to use with my phone and iPads, and i’d Like to make an informed choice. I don’t think I care about having an MQA capable DAC, but I wouldn’t disqualify an MQA DAC.


(Sean) #2

Hi Steven

I use this every now and then (iPod Touch + Apple Camera adapter) so I’ll try to help.

If you’re using the iPhone/iPad’s internal DAC, Roon will down-sample anything you play that’s higher than 16 bit 48kHz down to PCM 16/48. That’s the internal DAC’s limitation.

As above.

If using the iPhone/iPad’s internal DAC, even if you have Roon do the MQA 1st unfold, Roon Core will still down sample everything down to 16/48kHz before outputting to your iOS endpoint.

The newer iPads don’t sound too bad actually using their internal DAC (apparently measure well too) but when you use the Apple USB 3 camera adapter with a USB DAC, things get more interesting !

I can play PCM 32bit 768kHz (Roon up-sampled obviously) and DSD256 over my WiFi network to my iOS endpoint, to my USB DAC connected via Apple camera adapter. And my USB DAC will show incoming PCM768kHz or DSD256 sample rates.

Your WiFi network’s reliability and what your USB DAC supports will likely be the limiting factors more than the iOS+camera adapter’s USB output. Roon Core can still do the MQA 1st unfold and then do Roon DSP to your iOS endpoint, if you want.

Yep, if your MQA DAC can function as a renderer. Some MQA DACs only function as decoders only, some as both decoder AND renderer and some renderer only. But Roon + MQA will work with whatever your MQA DAC can support.

Hope that helps!


(Steven Goff) #3

Thanks very much, that helps a lot!


(Marco) #4

Hi,

I have the “standard” Apple MD821ZM/A Lightning to USB adapter.

When in Roon I try to run a DSD to the iPhone/iPad endpoint, it will convert the DSD to PCM.

If I go in the settings of the device the “DSD support” is “Not supported”.

If I will buy the “Lightning to USB 3” adapter I will have the “DSD support”? How Roon see the iPad/iPhone settings in the “DSD support”???

Roon should not see over the Apple device so how it will know that there is a DSD capable dac?

In fact, not only Roon doesn’t see the iPhone-Mojo as DSD capable but it also doesn’t see the Mojo 32bit capable (only 24bit are allowed).


(Sean) #5

Apologies for my error - I made a silly mistake above. My iPod touch can bridge PCM768kHz but only at 24bit, not 32bit - that’s an iOS limitation.

Can you share screenshots of your device Roon settings ? Do you have DoP enabled for the Mojo?


(Marco) #6

No issue anymore. It simply works with DoP. The only limit remain 24bit… but I think that iPhone will be better as endpoint than any computer so I think I can live with it (also because I don’t use DSD almost at all).