iPhone -> Lightning/USB 3 adapter ->DAC is it bit perfect?

[NiagaraPete]

I mean is that normal that I can change volume from iPhone?

Yes. You can also turn off the other phone sounds but I can’t recall that setting off hand.

 

[DiN]

Maybe the issue is Rotel's USB input?

DAC is supposed to claim IOS equivalent of WASAPI - the volume is disabled.

I will check all of my DACs - I remember that one of them allowed me to control volume on the iPad, just can't remember which one.

Added: I can report that my DACs that allow for volume control on the iPad are:

1. Modern unit built around a vintage AD1865 DAC, with XMOS108 USB board.
2. Musician Pegasus
3. SMSL M300

At full iPad volume they certainly all sound undistorted with Apple Music.

Gustard X16 and Oppo UDP-205 lock out the volume on the iPad. Both sound undistorted.

Hello, recently tested iPhone with my preamp (Rotel RC-1590). Streaming service - Apple Music.
If I connect iphone to preamp via lightning-usb charging cable to the front USB-A input - I'm getting 44.1khz max sample rate, iphone charging, but iphone also can't control volume.
If I connect iphone to preamp via back USB-B input with this chain (iPhone -> Lightning/USB 3 adapter -> USB A - USB B -> Rotel) I'm getting up to 192 khz (as it shows in my preamp), but I can control volume from iphone and also I hear sounds from iphone (when you tapping on keyboard for example) on my speakers.
Is it actually bit perfect or the sound is going through the iOS mixer first?

Possible help for anyone having issues while using USB cables. The USB cable-lengths/quality will matter as I've read in other posts. USB2.0 cable lengths of 2m or less are recommended (for USB1.0 cable it's 1m or less). JohnSwenson/audiophilestyle: quote,

"I would recommend 6Ft (2m) and under. The protocol used to transfer audio data over USB does NOT have any kind of error correction. I did a study of of about 12 different USB cables (none of them expensive audiophile types). Above 6ft I started to get occasional errors and above 10ft I got frequent errors. The only exception to this was Supra, a 10ft Supra showed no errors, but ALL the other cables were showing frequent errors at 10 ft.

None of the cables 6ft and under showed any errors at all.

Note that the audio protocol is very different than all the other protocols used in USB, the others DO have error correction so you can go with longer cables and have error free connection, but not with audio."
(end quote)

The 3m "Supra"(a Swedish maker) USB 2.0 cable ($72, found on ebay from US distributor "sjofnhifi"). I bought the 2m version, they also have 1m.
For longer USB runs(10m/30ft), people seem to use a Corning Thunderbolt USB-C Optical Cable with no errors, but it's costly at $300-$400 for the single cable.

When USB cables are involved, it's possible that audio issues are caused by using a USB2.0 cable length of over 2m(6.5ft), or a lower-quality USB printer cable. Audio-specific USB cables of 3m(or more according to some expensive audiophile USB cable makers) might produce results with no errors depending on make, but the shorter the better like with most cabling. One problem is static-build up in USB cables of longer-lengths and/or poor-quality that can fry DACs or other audio components. USB protocol also has cable-length limits--requiring active extenders for longer-distance runs, which I wouldn't trust to run my audio through. I limit my USB cables to 1m-2m, maybe in a pinch get a higher-quality 3m audio-specific USB cable.

 

[Enstip]

Possible help for anyone having issues while using USB cables. The USB cable-lengths/quality will matter as I've read in other posts. USB2.0 cable lengths of 2m or less are recommended (for USB1.0 cable it's 1m or less). JohnSwenson/audiophilestyle: quote,

"I would recommend 6Ft (2m) and under. The protocol used to transfer audio data over USB does NOT have any kind of error correction. I did a study of of about 12 different USB cables (none of them expensive audiophile types). Above 6ft I started to get occasional errors and above 10ft I got frequent errors. The only exception to this was Supra, a 10ft Supra showed no errors, but ALL the other cables were showing frequent errors at 10 ft.

None of the cables 6ft and under showed any errors at all.

Note that the audio protocol is very different than all the other protocols used in USB, the others DO have error correction so you can go with longer cables and have error free connection, but not with audio."
(end quote)

The 3m "Supra"(a Swedish maker) USB 2.0 cable ($72, found on ebay from US distributor "sjofnhifi"). I bought the 2m version, they also have 1m.
For longer USB runs(10m/30ft), people seem to use a Corning Thunderbolt USB-C Optical Cable with no errors, but it's costly at $300-$400 for the single cable.

When USB cables are involved, it's possible that audio issues are caused by using a USB2.0 cable length of over 2m(6.5ft), or a lower-quality USB printer cable. Audio-specific USB cables of 3m(or more according to some expensive audiophile USB cable makers) might produce results with no errors depending on make, but the shorter the better like with most cabling. One problem is static-build up in USB cables of longer-lengths and/or poor-quality that can fry DACs or other audio components. USB protocol also has cable-length limits--requiring active extenders for longer-distance runs, which I wouldn't trust to run my audio through. I limit my USB cables to 1m-2m, maybe in a pinch get a higher-quality 3m audio-specific USB cable.

I’m not so sure about some of this. I’m not saying you are wrong, but it doesn’t rhyme with me. I think a lot depends on the master and slave devices and how well they are implemented, and not the cables. Though USB C cables have a chip in them so that can be implemented badly as well, in cheap cables. That’s why I use an Apple USB C to USB A adapter, so I can then just use a standard A to B printer cable, which is ….. just a cable - no unknown chips in the loop.

So, my chain is from my iPad mini 6, through the Apple video adapter and into a bog standard 4m long USB A to USB B lead and into my DAC. I did have a 1m long supra cable (lovely quality cable like you say) and did a back to back between it and the 4m cable, and could not discern any difference. Also, my DAC is an “RME ADI-2 DAC FS”. RME allow download of some test files that the DAC firmware recognises and knows the bit content of, so when they are played it recognises them and flashes up on the display whether they were received bit perfect. There are a few files of different sample rates, bit depths, volumes etc. I tested my cheap 4m cable and it’s bit perfect. Perhaps I’m just lucky.

Interesting stuff though, whatever the opinion.

 

[bokolobs]

I used the Lightning to USB 3 Camera adapter with my iPhone 13 and iPad. Sadly, AM doesn't lock the volume control with my DACs:

1. Denafrips Ares II
2. Topping E30
3. JD Labs EL DAC II

Why does AM lock volume control on some DACs and not in others? Is this purely DAC dependent?

 

[staticV3]

Why does AM lock volume control on some DACs and not in others? Is this purely DAC dependent?

If you plug a DAC with UAC2 hardware volume control into an iPhone, iPad, or Mac, then the default systemwide volume control will continue working.
If instead you plug in a DAC that does not have UAC2 hardware volume control built in, then the OS will lock volume to 100%.

Not sure what AM is

 

[bokolobs]

If you plug a DAC with UAC2 hardware volume control into an iPhone, iPad, or Mac, then the default systemwide volume control will continue working.
If instead you plug in a DAC that does not have UAC2 hardware volume control built in, then the OS will lock volume to 100%.

Not sure what AM is

Thanks! AM is Apple Music. Trying to get it to work in bit perfect stream.

So does it mean that the volume being controlled in the iPhone is adjusted in the DAC?

 

[staticV3]

So does it mean that the volume being controlled in the iPhone is adjusted in the DAC?

With UAC2 hardware volume control, you remote control a DAC's digital hardware volume, so the volume control that's built into the DAC chip, from your USB Host device.
This is supported natively on Windows, iOS, macOS, and Linux. On Android, you need an App like USB Audio Player Pro to make use of it.

 

[bokolobs]

When an iOS device's Apple Music

With UAC2 hardware volume control, you remote control a DAC's digital hardware volume, so the volume control that's built into the DAC chip, from your USB Host device.
This is supported natively on Windows, iOS, macOS, and Linux. On Android, you need an App like USB Audio Player Pro to make use of it.

Ahh so the attenuation happens in the DAC? Thank you so much for this clarification!

 

[Srikanth]

I mean is that normal that I can change volume from iPhone?

I am also facing this issue. When i connected my ipad air 3 with external DAC through lightening adaptor, the sound quality is low when compared to ipad air 5 with usb C cable.
i seriously wonder if bits are bits as long as they are properly reached the DAC, why is difference in sound quality.
I did blind test before confirming yhis statement. Usb c is noticeably better than lightening for audio quality.

 

[Enstip]

Perception of sound quality is very much affected by volume. Are you sure your back to back tests are at the same level? You can get Apps that measure sound pressure and give you a real-time sound level readout. If you haven’t already, it might be worth repeating your tests and ensure equal volume using one of these Apps.

 

[thepiecesfit]

Does the thinner version of that same camera cable work? Little less bulky.

Lightning to USB Camera Adapter

Lightning to USB Camera Adapter lets you import photos and videos from a digital camera to your iPad. Get fast, free shipping when you shop online.

www.apple.com

 

[Enstip]

Stretching my memory here, but I recall something about the Apple device needing the capability of being powered by the adapter, even if no power source was connected, in order to operate reliably / provide full functionality. Whether that is true I can’t be sure, and it may just apply to older versions. The larger adapters do, of course, allow you to charge and listen at the same time.

 

[staticV3]

Does the thinner version of that same camera cable work? Little less bulky.

Lightning to USB Camera Adapter

Lightning to USB Camera Adapter lets you import photos and videos from a digital camera to your iPad. Get fast, free shipping when you shop online.

www.apple.com

In my experience, that adapter only works with USB devices that have their own power supply. If your device draws current from the USB host, then that adapter will give you an error message and will not work,

 

[Enstip]

Ah, that makes sense and tallies with my recollection of needing to be powered for full functionality. Thanks for confirming.

 

[thepiecesfit]

In my experience, that adapter only works with USB devices that have their own power supply. If your device draws current from the USB host, then that adapter will give you an error message and will not work,

Interesting but with a DAC like the Topping DX 3 pro + would it still need to supply power to the usb dongle? I'm just trying to figure out options eventually I'll replace the phone with something that has USB-C

 

[Broken Arrow]

A question about the Apple CCK USB 3.0 adapter, if I connect a charger to the adapter while connected to my DAC will it introduce any noise, I have another USB-C dongle from DDHifi which support simultaneous charging but it is very noisy when I connect the charger making the audio unlistenable.