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USB connection to Mac/PC and latency
by marcusdepaula on 2012-09-30 07:41:55

I have successfully connected my MacBook Pro running 10.8.2 to the StageScape M20d via USB and am seeing all inputs.  I also found on this forum how to select outputs 19&20 via Audio MIDI app in Applications>Utilities so that I'm getting the stereo bus of the M20d instead of inputs 1 and 2.

I would like to suggest if possible a way to designate the stereo bus as the default channels when connected to Mac via USB - OR at least provide this information in the user guide!!!  I know this is a new product and all, but the user guide is missing a ton of information on connection options.  Is there a separate document I'm missing?  I know there's information in the FAQ, but not on the Audio MIDI settings information.  If it is there, it was not as easy to find as the forum post.  It would be helpful to add the information on the Audio MIDI app in the user guide.  It would also be helpful to include a link to the driver on the download section of the product page along with all the PDFs, which is where I usually go when setting up a new device.  This is my first Line 6 product to use and I find the documentation and support not as easy to get what I'm looking for compared to other manufacturers and their sites...

I am looking at using the USB connection on a new MacBook Pro Retina (that has no analog audio input jack) to feed a Ustream video stream of a corporate event.  HOWEVER, in testing the connection today, the latency is UNBELIEVABLY BAD!  It's got to be close to half a second!  I tap a mic and it takes half a second to register on the core audio input meters in system preferences.  Obviously the delay is there when I open GarageBand to hear the audio quality.  I can't find any buffer settings on the M20d itself and there don't seem to be any in the Audio MIDI settings panel for the M20d.  I have tried adjusting the sample rate and it doesn't seem to affect the latency at all.  Since the audio has to sync with a video input, I don't think this will be a viable option for us.  So I'll have to go buy a cheap USB AD converter for this unless you guys have a solution that I haven't been able to find.

I notice that the USB to computer output selection shows up under the Record > Configure Record/Playback... window on the mixer itself, but as far as I can see there are no adjustment settings there.  Also, I've noticed that it disables the ability to record to the SD card, which is understandable.  Is that stated clearly in the recording section of the user guide?  I didn't see it.

Please advise. Our event is in a few days from now (today is 9/30/12).

Re: USB connection to Mac/PC and latency
by ArneLine6 on 2012-09-30 09:02:25


On this website under">">  there is a StageScape Advanced Guide with a chapter about recording and streaming:

The M20d streams 20 inputs to your computer and a stereo return stream back to the M20d in the following input streaming channel configuration:

  • Channels 1-16: M20d Mic/Line Inputs 1-16, pre-processing / pre fader
  • Channels 17-18: M20d stereo Aux Input, pre-processing / pre-fader
  • Channels 19-20: M20d stereo Main Outs, post-processing / post-fader

If the Main Mix was streamed to USB 1-2 as default a multitrack recording of the inputs would be difficult with L,R, Input 1(usb 3), 2 Input 2 (usb 4), etc.

It seemed better to have a clear relation between input and usb channel.

The Audio Midi Setup is the MacOS tool that Apple provides for these settings  so we can not change it.

On the latency side: Yes, it is bad. The USB connection was intended as a way to record and not as a live split or for any real time application. It would obviously be very useful to have the option to use the USB out for live streaming stereo or even a broadcast mix and we are working on this. At the moment the only low latency outputs are the analog and Line6 Link ones.

I did a Ustream with the M20d 2 weeks ago and used the analog outputs.


Re: USB connection to Mac/PC and latency
by marcusdepaula on 2012-09-30 09:36:19

The Advanced Guide was what I was referring to that had insufficient information for the USB connection.  Just listing the outputs isn't helpful for many non-professional users since it makes no mention of adjusting the inputs for core audio use using the Audio MIDI app or the equivalent Windows program.  Of course, since the latency is so bad and it can't be used with anything but DAW software, maybe the writers chose not to include it since most users will use the DAW's settings to choose inputs.

Another software request then - PLEASE make it possible to pair the monitor outputs both for live low-latency use like our video streaming scenario, and for stereo in-ear monitors systems.  Expecting us to dial a stereo mix via two mono aux sends is pretty crazy - especially for in-ears since very often you have things panned in between center and hard left/right.

Also, you might want to mention that to use the SD card for recording you have to reformat it to FAT32 (which is stupid).  What is the technical reason that devices like this continue to use this outdated and severly limiting file format as opposed to ExFAT?  Can someone please explain this?

All of the FAQs explain the type of card to purchase (class 10, etc.), but they make no mention of having to reformat them since most all modern cards come formatted for ExFAT.  Please pass this information along to the manual and documentation people!!!

As someone who actually does analyze manuals and forums and other available documentation, for such a cool device that can do so much, you guys need to do a better job helping users learn how utilize the more advanced features!  I guarantee you the vast majority of users that purchase an SD card like I did and plug it in and get nothing will not think of trying to reformat to FAT32 like I did.  Especially if it's nowhere to be found in the manual.

Re: USB connection to Mac/PC and latency
by blomasky on 2012-09-30 11:00:31

Marcus, I just did a similar thing (used Livestream, no commercials!!!), here is what I did.  I took the 1/8" audio out of the mixer, fed it into the camera, then had the HDMI video connect to the MBP via a thunderwire connection (had to spend 300 bucks for the black magic box for that).  This worked for me, with the plus I could also record the video with mixer out audio on the camcorder memory card.

Good Luck


(in sunny Connecticut)

Re: USB connection to Mac/PC and latency
by marcusdepaula on 2012-09-30 11:11:42

Did you send from a Monitor send or two from XLR to 1/8"?  Is that what you're saying?  There's no 1/8" output on the M20d that I've seen.

That won't work for us anyway since he's using a couple wireless Logitech HD cameras - I'm not sure exactly how.  I just have to get him audio.

What we're going to do is either use my Apogee Duet to get audio into his Retina MacBook Pro, or he's going to purchase a Griffin iMic from Amazon so he can have that input option for future purposes.

And it's Thunderbolt, not thunderwire. 

Re: USB connection to Mac/PC and latency
by blomasky on 2012-10-01 06:29:13

ok, Note to self, do NOT respond to forum msgs after too many adult beverages on the weekend!  Let me try again.  I put a 1/4" splitter on the headphone jack, with adaptor, connected 1/8" to that and fed that to camcorder.  Yes, the cable is a Thunderbolt of course.  I find that this was the only way to get good quality, low latency HD into the computer.  (I have tried some USB webcams but they can not compare to the HD camcorder for the quality of the picture).

Good luck

The last time we did this, we were at a venue with too slow internet to stream in HD, so we lowered the quality a tad.  If you want to see the results, they are still saved at


Re: USB connection to Mac/PC and latency
by Turin on 2012-10-02 04:47:46

Yesterday I tried to use the M20d as a "usb interface" to record in the studio - what a nightmare! The latency is very very very bad!

Line 6 really needs to fix this ASAP cause, like me, probably lots of people bought this to use live and in the studio, and this way is not possible.

I sold a Focusrite Saffire Pro 40 to buy the M20d and now I'm stuck!!!

I also think that things are not very clear in the manual.

I agree with Line 6 that the "direct channel to usb" is easier cause you look at the M20d and you know right away which input to choose ( M20's channel 13 = Input 13 on the software ), but I still don't know how 17-18 is the Aux input, but it's also the Output of the PC/Mac .... ??? I wanted to hear the Mac output and I already had an icon for input 17/18 (Aux) and it was a little bit confusing because I was expecting this to be the AUX Input ( where I had an iPod connected ).

So please , Line 6, work on this cause WE really need it!!!

Thanks for doing great products.

Zé Miguel

Re: USB connection to Mac/PC and latency
by litesnsirens on 2012-10-12 23:44:27

Are you actually working on the latency???  What can we expect in the future??  I just bought an M20d today, I was hoping to use it for live and as an interface for my DAW.  I tried it out and there is no way.  Even if I set the buffer in my DAW to 32, the lowest setting the latency is over a half a second.  I figured I must be doing something wrong but there were no settings I could configure to impove it.  That's why I'm here, to see if there was something I didn't think of but it appears that's just the way it is.

I have 30 days to take this back but I'm thinking I only need one.  It's an expensive peice of gear and although I can already tell that for live the quality is top notch, I really do NEED this to perforn both functions.  I thought it would be great to monitor using the on board effects but be printing a dry signal, and it actually works.  If you don't look at the screen you can record and it feels like zero latency.  But then having to go in after each take and line the track up by half a second.  Once is one thing but every track? I can't imagine trying to punch in.  And then there's the issue of trying to find audio pieces to edit when they've gone by half a second before you hear them. Or even trying to mix when your fader adjustments are half a second behind.  I don't need to go on any further, suffice to say,  this is just stuff I realized in 30 minutes of trying to make it work.

I know the odds of getting an answer in time to stop me from taking this back tomorrow and getting a studio live 16.0.2 for about 1/2 the money are slim.  But just in case someone is monitoring this thread, and can answer something about the latency issue and a possible fix. 

Honestly, I hate to be that guy, you know the one that is sounding like a threat to take it back if I don't get what I want.  It's not that at all, I simply need to be able to use the board to record to my DAW.  If it wasn't for the fact that I love the idea of what this board can do for live settings, I wouldn't have even come on here hoping to find an answer, I would have just packaged it up and gotten ready to take it back.  I hate that I have to, if there was some glimmer of hope, I would consider holding out and trying to figure out an interim solution.  Man this is kind of ripping my heart out... I was really excited about this mixer... I envy all you guys that only need it for live use... SWEET!!!

The information above may not be current, and you should direct questions to the current forum or review the manual.