By-passing Internal DAC of Apple Products


#1

When it comes to digital audio and my DS I have used the Bridge, SPDIF, TOSLINK, and I2S connections on a regular basis. Without a computer (my iPad doesn’t count) in or near the listening room I had not used USB, but recently I tried it using my iPhone. I was listening to the CBC Music app and with my iPhone 5 it sounded OK. I just recently upgraded to an iPhone 7 and the app doesn’t sound as good. Maybe it was a bad day for me or the app, but it got me wondering, does the DS strip out the digital data prior to the iPhone’s internal DAC? In other words, do something similar to the Wadia 170 (and numerous other devices now). This seems like something that should have been asked a long time ago, but I do not recall it being discussed. My reasoning is some streaming services are awkward to use in JRiver and having an app that I connect via USB is an easy solution, but if I have to listen to the Apple DAC maybe it’s not the right solution.


#2

I would think it would have to bypass the internal DAC. I’m assuming you are using the Lightning connector to USB (with a special cable or some type of USB adapter). The DS can only understand a digital signal and that’s all the iPhone 7 puts out anyway so I don’t see what role the iPhone DAC could play. It’s not relevant to your situation but the iPhone 7, which did away with the headphone jack, does not put out an analog signal over Lightning. There is a DAC in the tip of the Lightning earbuds that comes with the phone or in the Lightning to mini-jack adapter.


#3

Hi, I’m a PC guy, but I know the Mac Mini is one of the most popular computers to use for music. Anyway, never mind that, I just reread your post again. I personally don’t know anyone who uses their phone for anything but control. The signal may go through some things before output, but not the DAC. No DAC can accept an analog signal through a digital input, and the DAC will take the data with a DS and convert it to DSD, so reclocking will be part of that. It can’t work miracles so if your phone is sending a noisy jitter filled signal, it can’t repair all of that. Look at the difference between transports and digital cables. Garbage in garbage out.

I would check all the settings, and see if there is an exclusive mode. A way to bypass the volume control. JRiver doesn’t work for streaming Tidal, and only Tidal’s desktop app gives you access to Master files, which can sound quite good with the first unfold. I think most other streaming is at Mp3 quality.

You should look into a stand alone streaming device. There are numerous ones available, check out Audio Advisor and/or Music Direct. Phones are designed to be used for mobility, not ultimate SQ.


#4

Thanks for the replies! I think Stevem2 gave me the Doh! response. Certainly makes sense now that he said it. The nagging feeling is there was such a big deal about the Wadia unit when it came out, but now there is no mention of it at all. I have a so-so Marantz all-in-one unit for use in my northern Michigan second home which does this and makes a point af saying it does. It certainly would seem like the DS should do this, but it’s not addressed. I’m not going to any extremes, i.e., buying a streamer, for this. It was an easy way around a minor problem.

Edit: Forgot to mention with the iPhone 5 I was using the Lightening connector, I know the headphone out would have been analog.


#5

I misread your original post and thought you were using an iPhone 7 rather than a 5. Same answer basically. I’m not sure iPods and iPhones always put out a digital signal that could easily be read by external DACs. That may have changed somewhere along the line, which could explain why there were previously DACs, like the Wadias, that were different in this regard. I seem to recall a demo by Krell (maybe–did they make DACs?) at an audio show many years ago using an iPod as a source that claimed the ability to access the digital files whereas contemporaneous devices could not. But then my memory could easily be faulty.


#6

Stevem2, you read it correct the first time. I had an iPhone 5 and just upgraded to the 7. My observation (in a very small sample size, i.e., one or two listens) was the 7 sounded worse. That got me thinking if the DS was actually getting a raw digital signal or something else. My take on your original post was I could only be getting a raw digital signal from the Lightening connector. At this point I’m taking that as the answer. I thought maybe someone from PS Audio would respond, but maybe I’ve got “the” answer.


#7

Just shows how bad my short and medium term memory have gotten. Also just too lazy to reread the post. confused It’s definitely a digital signal over the Lightning connector, for both iPhones.


#8

The issue with the iPhone is that the data travels through the iPhone sound mixer and gets significantly degraded thru conversion processes in the digital domain. You end up with narrow stage width and reduced dynamics. Damien, the programmer for Audirvana, cannot write an app to send out pure data due to Apple locking the iOS.

Getting stuff out - Onkyo Hi Fi sounds much better than Tidal or iTunes.


#9

Cxp, thanks for that bit of information! It could be they changed something in the mixer between the iPhone 5 & 7 that accounts for the sound difference. Perhaps some experimenting is in order!


#10
pmotz said

Cxp, thanks for that bit of information! It could be they changed something in the mixer between the iPhone 5 & 7 that accounts for the sound difference. Perhaps some experimenting is in order!


There are a ton of variables. Don’t forget internal hardware, battery placement, EMI, all can impact noise going down the digital path. Heck, if there is more crap crammed close together in the 7 vs the 5 series.

And definitely if the software has changed with the mixer or the digital path. If the code got more complicated or there are more steps through iOS it may impact.

Android might be better, there is an app that allows for exclusive mode and bypassing the volume control. Apple won’t allow an app to do this.