Q: El Capitan USB audio problems.

To be clear: it is still just a guess. Not all problems mentioned here might be caused by the same issue. May be one of the users just has a bad usb cable.
Having said that, many devices don't work and all devices of which I can find the chipset are USB 1.

In the OS there is a generic USB audio driver and I expect this driver to be the issue. It can be that it doesn't function anymore with USB 1 speed products and/ or that the usb audio protocol v1 isn't implemented anymore.
I don't know whether other USB 1 products function still, but I would expect so.

I would say that your midi/usb product could be affected, it is properly the same protocol/ driver, but am not sure.

-  Is there a way to upgrade the chips in our products to be USB 2 compliant?
Practically not.
I could imagine for some devices to add a circuit board that does conversion from USB to I2S and inject that in the DAC, but it would be very challenging.

- Is there a way to build a USB 1 - 2 conversion device that would make OS think that there is a USB 2 device connected?

Interesting thought, practically not, I would say.

I'm honestly not sure what Apple....

Clean up the house. Old technology becomes a burden. If you don't support it, it won't give you trouble. What they fail to understand is that some external devices last way longer than their own stuff.

"is most unprofessional..." To my opinion Apple hasn't taken business continuity serious enough on previous occasions as well. This creates a lot of distrust with professional users. A clear example is final cut and motion, where many users have doubts about Apple's commitment to video and film production in the long run.

I’ll back you up in saying I found a thread on the dev forums that 1.0, 1.1, and older 2.0 devices may not work with El Capitan from all the way back in June: https://forums.developer.apple.com/thread/4062

Also “The Element” from JDS Labs does use a UBS 1.0 (or 1.1 I’m not sure) controller so that would explain why my DAC isn’t working as well.

FWIW - I have a 2014 MacBook Pro now running El Capitan and I am unable to use external USB CD/DVD drives to rip audio CDs - I get lots of audio artifacts such as clicking, posting and skipping (for want of abetter way to describe what I hear). These drives work fine on an older 2007 MacBook Pro running Mountain Lion. The Apple response of "it's a drive problem" would sound reasonable if devices like CD/DVD drives didn't all implement the standard USB interface (these are high-end drives from OWC and Sony, not some cheap non-name brand).

My post isn't helpful to provide a solution, other than to say go get an older Mac running one of the more decent OS releases (or get a Windows or Linux box that doesn't seem to have these issues). It used to be that I would reboot my Windows systems at least daily, now they stay up for weeks and I'm rebooting my El Capitan Macs often to fix USB, WiFi and video problems. But I take comfort in the fact that the user experience (frequent reboots necessary) on my Macs matches the user experience on my iOS devices.

I did a complete reinstall of OS X 10.11.3. The first time I plugged in my Element the issue happened, but after reconnecting it I have not been able to reproduce the issue. Additionally, I tried it on three USB 3.0 Macs and I could not reproduce the issue. It seems it might be an issue with Macs that only have USB 2.0 ports such as the MBP that I originally had the issue with?

It is a pity I can not enjoy sound with my Apogee Duet and good KRK speakers and instead have to listen to music through built-in thunderbolt display.

The reason is the same: audio is constantly disconnects.

Very sad for Apple becoming just another flop.

Are you using the Duet or the Duet 2?

Duet 1 is a FireWire device so shouldn't be related to this problem, I'd think.

That said, I use a Duet 2 (original pre-iOS compatible version) everyday for both listening, recording, and monitoring and I'm having no issues (El Capitan 10.11.3). So strange. I also use a Groove at my office with no issues and use a One (v2) regularly and haven't had any problems.

What kind of Mac are you using?

MBP, Late 2013, 15'

Just right now when I tried to launch this browser window, the sound card disconnected twice. With my speakers on

I'm afraid for me there's nothing left to do but downgrade to Mavericks and never-ever again update to anything new from Apple.

Updated to 10.11.3 and my NuForce uDac 2 has been working flawlessly for the last hour or so (for the first time since upgrading to El Capitan).

Cautiously optimistic that apple may have finally fixed this. Good luck everyone.

For my AMP/DAC if you change the volume on the Mac as the AMP is turning on and the DAC is plugged in the issue will surface and not go away. However, the issue is only isolated to that one USB port that the DAC was originally plugged into. Other USB ports work fine until you change the Mac's volume while the AMP is off or booting up.

Additionally, the only way I have found to fix a "broken" USB port is to reformat you whole computer and reinstall OS X. I'm not sure if just reinstalling OS X over your current install would work, and I'm not sure if there are any terminal commands that can be used to "reset" the USB ports.

Can any of the experienced users here answer why my USB DAC NuForce uDac2 works ONLY when plugged into my Apple Wireless Keyboard A1243? Does this mean that maybe we could solve this issue using some kind of USB hub? What would the specs for the hub need to be? (I have the same problem as everyone here, DAC stopped working with upgrade to El Capitan)

Puzzled: A1243 seems to be a wired keyboard, if I look at mine....?

Sorry, I meant "wired", as it has USB ports :-)

Could you perform this small test:

- disconnect the usb-keyboard from the computer, wait a while

- connect the DAC to the port the keyboard was connected before

- put the keyboard in any other usb-port available.

- wait a while

Does the DAC work?

I have just tested most of the options available, including both my MBP 15" ports and my Apple Display. Even combining ports on both, nothing worked, always ended up with the device popping ON/OFF in the SOUND output MENU. Although the DAC worked fine while plugged in through any of the two ports on my keyboard no matter if it was plugged into the display or the notebook itself. It seems like the keyboard is doing something that makes the PC cooperate with the DAC. Or better said - it bypasses some strict rules set by Apple to be monitored directly in the USB ports

Updated. No help. Soundcard still re-connects while opening different apps (like iTunes).