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I've had the same problem since i switched from windows to mbp. Just until yesterday! I upgraded to macOS sierra and it is finally gone!

That's good to hear!

It's a mystery till now..

I just got the answer from Korg support, the problem exists on MacOS Sierra since 10.12, it is known and they work on it. So all we can do is wait or use a PC or external sound interface for that.

slimhan wrote:I upgraded to macOS sierra and it is finally gone!

Hmm, according to Korg - not

Thanks, looking forward to a solution!

Danatkorg: I mostly only play for home-enjoyment with Omnisphere/Keyscape. So no heavy audio recording. When I do record some audiotracks via the MOXF there is no problem. SSD + 16 GB RAM is sufficient for my use.

I had the problem where the USB audio from Mac to Kronos goes glitchy after a few minutes. After reading around a bit it seemed that Apple introduced an interoperability bug in their USB Audio driver in 10.10 which affected certain audio interfaces. There are various posts on other forums describing the same problem with other USB audio devices on OS X, besides the Kronos.

I worked around it by replacing my /System/Library/Extensions/AppleUSBAudio.kext with the one from 10.9.5. With later versions of the driver, the clock drifts out of sync after a few minutes but so far I've not had any problems with the older driver.

Here's what I did. I don't recommend it though, because I had to turn off the signature verification for drivers in order to get it to load the older kext. So please only consider doing this if you're sure you understand the risks.

Downloaded the last combo update for 10.9 (https://support.apple.com/kb/DL1760) and extracted the AppleUSBAudio.kext from it using Pacifist (https://www.charlessoft.com/). I believe the kext in this rollup update is the last version which didn't suffer from the interop bug.

Copied the existing /System/Library/Extensions/AppleUSBAudio.kext to a safe place in case it needs putting back for any reason.

Disabled System Integrity Protection. This is a really bad idea and you shouldn't trust anyone who tells you to do this :p Unfortunately I had to do it in order to replace the existing AppleUSBAudio.kext (because I couldn't remove the immutable attribute from the existing kext otherwise) and to get it to load the new one, since even though the older kext is signed by Apple, the newer OS seems to have some problem verifying the signature.

Checked that the old driver could be loaded and worked OK (sudo kextunload AppleUSBAudio.kext && sudo kextload /path/to/extracted/AppleUSBAudio.kext)

Copied the extracted AppleUSBAudio.kext to /System/Library/Extensions and rebooted. (I couldn't find a better way to make it load the old kext while leaving the up-to-date one in its proper place.)

EDIT: I haven't tried again with the 10.12 driver since updating to Kronos 3.1.2, but I didn't see anything in the release notes which would suggest that anything to do with USB Audio has changed. When I updated my Macbook Pro from 10.12.2 to 10.12.3, the AppleUSBAudio.kext got replaced with the latest one again and the problem came back, so I had to copy the old one back again. That's another drawback with this workaround :/

Hello Sengi, thanks for your answer and explanation. Quite a story! Good to hear that this worked. I'm not sure yet if I have the courage to do this but I will look at it with some assistance. What puzzles me is that as far as I know this problem does not occur to all Kronos users. I wait for an answer from Korg and from my dealer, and will post it here. Thanks again for your explanation how to change the AppleUSBAudio.kext, maybe this is the final solution!

Facing the same problem as Jaap with similar setup:

Macbook Pro Early 2011
macOS Sierra 10.12.4
Kronos 1 with 3.1.2 firmware

I am not willing to follow sengi solution due to signature verification bypass.

Anyone found another solution?

Hi Nambuco67,

I am still waiting for a reaction from Korg. My dealer has sent my describtion of this problem to their Korg salesman. I will post the answer here. And hope to receive a solution, because it is too bad that the Kronos can not be used as an audio interface in the setup with the Mac.

Bye, Jaap.

Thanks Jaap for the update.

Just another info, I am using Logic Pro X.

nambuco67 wrote:Facing the same problem as Jaap with similar setup:

Macbook Pro Early 2011
macOS Sierra 10.12.4
Kronos 1 with 3.1.2 firmware

I am not willing to follow sengi solution due to signature verification bypass.

Anyone found another solution?

The Sierra USB/audio problem has caused considerable headache. It is completely due to Apple and Sierra

I cannot go back to Mt Lion, etc, etc.

There are 2 post topics from last week on this forum that bang on this topic thoroughly.

There are 1 or 2 options. read the posts from last week

Thanks Greg,

I rechecked those topics, and tested again the solution proposed by Pedro, using aggregate, but after some minute the problem is always there, a terrible noise.

I will test optical audio from Mac to Kronos or eventually buying a FCA1616 that has optical in / out....

nambuco67 wrote:Thanks Greg,

I rechecked those topics, and tested again the solution proposed by Pedro, using aggregate, but after some minute the problem is always there, a terrible noise.

I will test optical audio from Mac to Kronos or eventually buying a FCA1616 that has optical in / out....

I guess you are trying to get Logic to recognize Kronos as a virtual instrument ?

I am not familiar with using the Optical but a good audio interface seems to be the best work around.

GregC wrote: I guess you are trying to get Logic to recognize Kronos as a virtual instrument ?

I am not familiar with using the Optical but a good audio interface seems to be the best work around.

No, I am just trying to use Kronos as a mixer and avoid analog signal between Macbbok and Kronos and also because I have analog inputs from Kronos are plugged on a PA900 outputs. Kronos outputs goes to speakers.

nambuco67 wrote:
I rechecked those topics, and tested again the solution proposed by Pedro, using aggregate, but after some minute the problem is always there, a terrible noise.

Just to clarify this....it does work fine with Mountain Lion and audio can be routed from the mac into the Kronos,via usb, using the Soundflower app.,but not with sierra,unfortunately.

The crux of this is how audio is routed within the mac which needs to be sent out via different channels to avoid any loopback/feedback/howl-round effect(or whatever the correct term is).
Soundflower provides alternative outputs which keeps things separated.

I've tried other similar(free) audio stream routing apps,with sierra,but without success.
There are paid for apps,but they remain untested.

Best Wishes.

Understood Pedro.

Let us wish Apple / Korg come to a solution. Tomorrow I will try an optical cable between Macbook and Kronos...