Alex,

....Agree, unless it is Native USB3.  That seems to be the trick - at least for disk drives.   But finding a native USB3 audio interface is difficult and spendy.   All of the USB2/USB3 compatibles seem to be upgrades and not true USB3.  

I recently saw an ad for a Native USB3 interface, but I haven't seen anything written about it to prove that  this is strictly a USB3 TO USB2 downconversion problem or if the USB3 audio driver is just plain bad.

http://www.musicradar.com/us/news/tech/musikmesse-2013-rme-madiface-xt-is-the-wo rlds-first-usb-3-0-audio-interface-573725

(Does anyone have one of these on a Haswell iMac?  This one's an experiment that I won't be doing.  $2.5k is way too much for me).

Message was edited by: cadpi

It's ridiculous to try and pin this problem down as on this thread. So many different manufacturers of Audio Interfaces.

I bought a Thunderbolt/Firewire converter for an Ensemble.

I bought the Firewire cable to go with it.

I did everything they said to do on the Apogee website including downloading the Mavericks update.

They state on the Apogee website that it works! I does NOT work. That's a total rubbish statement to make on your website.

I went back to the Apple Store 4 days ago. They told me in the store that they were unaware of the problem with audio interfaces and the Haswell iMac. That's the funniest thing I've heard in years. They are totally crap if that really is the case. *** planet can they be living on? Apogee don't seem to have tested anything pre-release either.

I wouldn't start messing round with splitting drives so I took it back nd got a refund. What a waste of time that was.

Hey Rafael S,

Could you possibly send me a video of you using your interface with your SSD iMac? I'm compiling videos to send to Apple and tech blogs about this issue.

*****If anyone else has a 7200rpm HDD or SSD 2013 iMac and your interface works, please post a video or DropBox link of it working!

Thanks!

I contacted Apogee about the very same problem, here's their response:

"We recently are aware of an issue occurring with USB audio on the newest Mac models. The hardware specific issue does not occur on Mac's produced prior to Fall 2013. This appears to be affecting USB audio interfaces from other manufacturers as well as Apogee's. Our Engineering team is working diligently with Apple to get this resolved as soon as possible."

Apple issued OSX 10.9.1 today (see Software Updates) - I did not see anything related in the release notes but maybe someone can confirm (or not confirm) whether any issues with USB-Audio Interfaces have been silently addressed anyways.

EDIT:  I just downloaded the update myself and the problems persist on my end, that is:

Late 2013 iMac with split(!) Fusion Drive. Before the split, the audio interface was not usable at all, with split Fusion Drive the high-pitched distortions come up less frequently but they still do. Applying OSX 10.9.1 did not resolve this issue.  I will try hooking up a different USB-Hub tomorrow.

-act

Unfortunately, Apple's detailed release notes page for the 10.9.1 Update is broken.

I've got it installed now and will test it to see if the problem's been addressed but I am doubtful.

***10.9.1 does not fix any of the audio interface issues.***

A registered developer who already had access to 10.9.1 told me a week ago it did not.

I tried it just now as well with my Avid MBox Pro 2 (Firewire > Thunderbolt), no luck.

By the way, this is not just a USB issue... it's Firewire audio interfaces too. Most users who have the fusion drive are experiencing this audio interface problem, if you read all the way back to the beginning of this thread...

Most SSD and HDD users are reporting their audio interfaces are working fine.

Hi Adam - splitting the fusion drive did not entirely resolve the issue for me as pointed out above. I seem to be one of those who have a mix of different problems - one being the Fusion Drive, another the USB3.0 streaming. Oh well...

-act

Dang... What's your audio interface? And which iMac do you have?

I now use an Allen & Heath QU-16 - which is actually a digital mixer but also incorporates DAW-compliant USB-Streaming and can be used as Audio Source on OSX - it's a  pretty new machine too.

I had a Fireface UCX before which also failed to work properly when FD was still in place. Since I sold that one a few weeks ago I did not happen to test the UCX with the split Fusion Drive. 

Anyways - my last hope is to use another powered USB hub to put inbetween the mixer and the iMac.

-act

You are probably right.

If that does not work, try installing Mavericks on an external...

Booting off an external worked for a guy who posted in this thread a month ago:

Carbon Copy Cloner by www.bombich.com

*Temporary Fix # 2: Clone Your HD and Boot Off USB3 or Thunderbolt External Drive*

Just cloned my drive and booted off my USB 3 external. My Digidesign (Avid) MBox Pro 2 cut out in the first 10 seconds... But I then reset my settings for my Avid MBox Pro 2 in System Preferences from Internal to Wordclock, back to Internal and it seems to be working for now... Actually longer than it ever has.

Here's how to do it:

http://lifehacker.com/5926945/build-the-perfect-portable-powerful-mac-then-carry -it-in-your-pocket

Carbon Copy Cloner has a 30 day free trial:

http://www.bombich.com/ccc_features.html

Downsides:

1. Had some strange glitches at first... Failed to boot up the first time... Second time worked.
2. Slower iMac. All my apps and folders on my desktop took a long time to show up, but maybe it was only cause it was the first time it fired up. I would suggest buying a NEW external. The one I used is a few months old and used to have information on it... I did a Disk Speed Test and it significantly reduced to 90 MB/s write and 95 MB/s read from 200 MB/s (read) and 700 MB/s(write).
3. Logic Pro X opened up slower
4. You still have your internal drive that your iMac came with, but you cannot use it while you boot from your external. You can always boot from your internal again.

Advantages:

1. You can plug your boot external to any mac and it will be exactly how you left it on your iMac.
2. RAM performance still works great in Logic Pro X and Pro Tools 10...
3. Still have some use of the Fusion Drive...

I will update you if it continues to work or not. Crossing my fingers...

My Specs:

2013 iMac 27" 3.4 GHz

iCore 5

16GB

3TB Fusion Drive

*Note: 2012 iMacs with the Fusion Drive have ALSO reported audio interface problems...*

Just saw this on a tech support page (September 25, 2013). http://support.apple.com/kb/TS5166:

iMac (Late 2013): iTunes audio distorts via Thunderbolt display

Symptoms

iTunes audio may have distortion such as pops, crackles, or drops when played through a Thunderbolt display.

Resolution

                           To correct this issue, download and install the OS X Mountain Lion v10.8.5 update. To do so,                                    choose Software Update from the Apple () menu

Got to be kidding me...

Update:

Have to say booting of my external fixed my issue 100%. I'm happy