Q: El Capitan USB audio problems.

Wiped the hard drive clean and did a factory fresh install of el capitan, updated to 10.11.3, plugged in  usb dac, no difference,  still just flashes off in sound preferences. This has been an known issue for 8 months now and not a peep from apple.... wow.  I don't even care if they fix it anymore, I just want an answer, no we won't fix it or yes we are working on it, not saying anything is so unprofessional.

which just proves again: stay on what's working stable and do not believe their new updates of "the perfect OS ever existed"

That's really weird as a clean wipe worked for me. Was you AMP on when you plugged in your DAC? Did you change OS X's volume levels before turning on the AMP? I'm just curious to as why formatting worked for me and not you.

Zoom R24 now working as a control surface in Logic since fresh install of eE Capitan...hoorah!

Having issues with a USB microphone, Blue Yeti. It just goes silent after a while during recording sessions, sometimes after 5 minutes, sometimes after 10 or 15, and other times its fine for a few hours before it just dies.

And if it does work, sometimes the audio just starts clicking and clipping all the time with no settings changed, rendering the eventual commentary track useless. Never had these problems on Yosemite, and this is a new microphone after the previous one developed a fault from sheer age. I'm now contemplating downgrading to a clean install of Yosemite because this is ridiculous. Core Audio is clearly buggered and possibly even the USB control system.

I've adopted previous OS upgrades early on and nothing broke, what is this rubbish?

El Capitan? More like El Catastrophe.

Well I found a fix  for  my NuForce UDac3 not being recognized. Hope this works for everyone as well. After much frustration  and realizing the unit  works fine on my windows computer.. I plugged a usb2 hub into the usb 3 port on my Mac then plugged my UDAC3 into tone of the usb2 hub ports. I then went into Settings/Sound and there it was! Recognized!

The hub i'm using is a cheap (Orico 4 usb hub) but now I'm in business.

I'd be interested to know if this works for  others.

Oh  yes sorry, I'm running a MacBook Pro (2015)with El Capitan 10 version 10.11.3

Above I said I plugged into tone, I meant I plugged into one of the usb ports.

  "El Capitan adds some security improvements that should make OS X more resistent to exploitation by malware, but it will also mean a change or end to some software utilities on which you may rely."  

I am fairly certain all of these usb issues are related to changes in apple SIP (System Integrity Protection).  I'm not computer savy enough to give it a try but you can boot into recovery mode and disable SIP, reboot and try your audio software.  I bet this would solve the issue but who wants to run a system without security protection from malware.  

I think that I have found a solution, I have been having problems with my external DAC from the very start with el capitan, I ran a variety of diagnostic tests and discovered that the root of the problem is that apple's core audio is not fully class compliant with usb audio. I stumbled upon this software: http://www.usb-audio.com/ and it is now working fine. This software includes a rewritten driver for usb audio that works with class compliant devices, it solved all of my issues. They have a demo version that has a periodic beeping noise, but the full version in 49 EUR ($54.51 at time of posting) removes the beeping. It is rather pricy for what it is, but it is the only thing that has worked for me after days of scouring the internet for solutions.

I also found the solution.

And it works brilliantly.

Just downgraded to Yosemite, and it really was worth it, now I can safely listen to music via Apogee Duet 2 without it losing connection

That's a great looking website, circa 1992?   Where do I give them my credit card information?

So, we now have two candidate workarounds.

1     insert a usb2 hub in the middle

2     buy a third party usb driver

Would be nice when more people can confirm whether it works for them or not. Also, if it doesn't work for them! Please be specific about the device you are using.

I have a Presonus 22VSL Audio Interface that not work with El Capitan 10.11.3 until today.

I use the Class Compliant Mode.app from the focusride side and after a restart my AudioBox 22VSL is back working in the system.

wonder why - i hope it helps

http://global.focusrite.com/answerbase/i-am-unable-to-use-my-scarlett-interface- as-an-inputoutput-device-on-os-x-1011-el-capitan

I've tried an Inoteck USB 3.0 hub, the built-in hub on my Dell U2415, and an Amazon Basics USB 2.0 hub and none of them work. My Nuforce Icon DAC didn't work with any of those.

For the time being, I bought an M-Audio Super DAC (which does work on El Capitan) I'm using purely as a DAC and then feeding analog to my Nuforce. DAC doesn't sound as good as the Nuforce, but at least I can enjoy my music again.

Connecting to a usb2 port made no difference.