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mattlach
11-15-2016, 01:49 PM
Hey all,

So, my fiance really liked the sound quality of my DAC/Amp/Headphone combo on my computer, so having suddenly created an audiophile I set her up with a nice little starter package of her own for her birthday, consisting of a Schiit Modi 2 Uber DAC, Schiit Asgard Amp and a 250 Ohm set of Beyerdynamic DT770 Pro headphones.

This is for her Late 2013 27" iMac (iMac 14,2)

The DAC supports USB, SPDIF and Optical Toslink. Because USB inherently has timing and interpolation issues when it comes to audio, I opted for the optical toslink connector, and ordered a mini optical to toslink cable.

The system sounds great, and she loves it, except for one little problem.

Whenever you plug the mini-optical cable into the 3.5mm port on the back of the Mac, it becomes the only audio output listed in the list of devices in System Preferences -> Sound. "Internal Speakers" are listed there before you plug it in, but plug it in and they disappear.

This poses an issue. Constantly unplugging and replugging cable is both inconvenient and difficult due to its obscured position on the back of the mac (it's partially blocked by her second monitor), and it is also not very good for the optical cable long term (and possibly not for the switch in the mac port either.

Ideally, one should be able to just leave it plugged in and switch between the two with a click of the mouse, and this is how it works if you use Bootcamp and install Windows (and Linux too, for that matter), so we know it isn't a hardware limitation, but rather a software limitation.

Something in either the OS itself, or in the driver (kext?) is - presumably for ease of use - disabling the Internal Speakers when something is plugged in, so Apple get's fewer "why am I not hearing sound" complaints from clueless users. Not a bad design choice, but there absolutely HAS TO be a way to override this behavior and return control to the user.

The question is how?

Switching to USB, or buying any additional hardware (speakers or otherwise) is not an acceptable solution for something that should just work in software.

I have been clicking through everything I can find looking for advanced options to no avail.

Has anyone else run into this problem? How did you resolve it? Are there maybe further advanced configuration files in text format inside the kexts? Or maybe a third party audio kext exists one can use?

I welcome any ideas at all.

Thanks,
Matt

KevinJS
11-15-2016, 03:32 PM
I use this feature any you are right. Plugging in optical output disables internal speakers. I never looked for a way of switching because due to space constraints, my Mac is too far away from my DAC.

So I AirPlay to an AirPort Express and keep the permanent TOSLink connection from there to my DAC.

I know you said no more hardware, but I can't think of another way.

KevinJS
11-15-2016, 03:40 PM
I'm not sure this is about clueless users, so much as giving you the opportunity of bypassing the internal DAC. I don't know which DAC is built into a Mac but I doubt it's of comparable quality to standalone DACs, which can cost thousands of dollars.

mattlach
11-15-2016, 07:12 PM
I'm not sure this is about clueless users, so much as giving you the opportunity of bypassing the internal DAC. I don't know which DAC is built into a Mac but I doubt it's of comparable quality to standalone DACs, which can cost thousands of dollars.

Well, whenever you use either copper SPDIF or Optical TOSLink you are bypassing the DAC, that's what those outputs are for. The Modi 2 Uber I am connecting IS an external DAC.

There is no need to disable the internal outputs whenever you bypass the internal DAC. That is evidenced by that this works the way I expect if I - on the same computer - use Bootcamp and Windows or Linux. It is only in OS X this problem exists, which means, "it's not a bug, it's a feature!" :p

KevinJS
11-15-2016, 09:29 PM
Yes, I know what the Modi 2 Uber is, and how it works. It fulfils exactly the same function as my DACMagic Plus.

Well, I guess I'm done here. I responded to your initial concern with the best permanent solution I could think of under the circumstances. By the way, the internal DAC on a Mac is supposed to be pretty good so you may not notice much difference if you plug a 3.5mm to stereo RCA cable into the headphone output and take it straight to the amplifier, bypassing your external DAC completely. The internal speakers still won't work, but who would care if they had Beyerdynamic headphones?