Hi B,
We can help you with the signal routing here, and we can explain what the options are and what they mean.

There are two different digital audio outputs available on the Motif XS. The multiple channel mLAN digital that return 16 buses to the computer and receive 3 stereo buses from the computer via a FireWire connection. And the SPDIF coaxial stereo digital output.

The 16 mLAN audio outputs are named "L&R" and "m1" thru "m14"... Stereo plus fourteen assignable outputs
Any OUTPUT SELECT assignment m1-m14 are not available to you unless you are using the FireWire connection. In fact assigning an XS PART to OUTPUT SELECT = an item m1-m14, actually takes that PART out of the stereo mix. It is the equivalent of re-routing the audio to a separate *direct* output. It is removed from the main stereo mix... You would do so in a FireWire setup when you want to record this PART discreetly to its own audio track in your DAW.

Whether or not you are hearing this "direct out" assignment is determined by the Monitoring Options you have selected. The XS can be heard direct, and it is possible to monitor signal routed discreetly to an assignable output.

There is doubling of audio routing that can occur in any recording scenario, including computer based systems. You have established two pathways for audio to travel. There is the normal path of the Motif XS to your sound system and there is the audio path that is routed to the computer for recording before it is sent to the speakers.

An audio interface is responsible for directing and redirecting this traffic. It's function is to take inputs from your source devices, and route them to the computer for recording and also to your speaker system for monitoring. You must make selections according to what operation you are doing, which path it makes the most sense to listen to at the time.

I will try to outline the most common scenario...

Recording your Motif XS performance using the Motif XS VST
Recording a MIDI track to your DAW. The key presses and controller movements travel to the DAW (Local Control) on the XS should be set OFF (to prevent MIDI doubling).
_The MIDI track in your DAW should be routed MIDI OUT = "1-Motif XS VST-Midi In"
_This routes the MIDI data to the Editor. You will know you are successful because as you play keys on the XS the Editor' keyboard will indicate the notes you are touching.
_The EDITOR VST > File > VSTi SETUP > you will select the driver ports for your audio interface. The MOTIF XS is on the left, use the first line Left and Right. In the center box you set your audio interface and the ports you have the XS connected to... You have the SPDIF so you have just two ports: Left and Right.

The SPDIF out is a duplicate of the main L/R analog output of the XS. Anything send to OUTPUT SELECT = L&R will go to the SPDIF. That's why there is not a "digital out" selection, "L&R" is the selection that automatically sends signal to both the analog and SPDIF stereo outputs. They are clones of each other.

By making the audio interface's connection on the VSTi Setup screen, you can see that the right panel shows the DAW. This is how audio is RETURNED to your DAW.

It will arrive as a stereo VST audio in... Via the Editor. It arrives in the VST INSTRUMENT folder, in the Motif XS VST subFolder... There is a stereo *Audio Lane* that represents the returning "virtual audio" - this is not an audio *track* because you only monitor the audio return. It is virtual audio because we have not yet written a wave file. You are able to listen to what it will sound like when you finally decide to MIXDOWN.

In most instances when recording in this scenario, you would opt to hear yourself "direct", rather than listening to the "virtual audio" coming from the Audio Lane. So you can press the "m" MUTE button on the VST INSTRUMENT Audio Lane.

Set your audio interface to monitor input sources "direct". Audio interfaces will allow you to select to monitor the return from your DAW (called the "latent" signal) or to monitor your source "direct". When playing you will probably want to monitor yourself direct.

In either case there can be doubling of signals... Midi doubling is prevented by working with LOCAL CONTROL = OFF. You use your DAW's MIDI TRACK to echo signal back to the tone engine (and MIDI CH) that you want to trigger.

Audio doubling is prevented by selecting to monitor direct and muting the "virtual audio" return (during the record process).
Of course, once you finished recording, you want to unmute the Audio Lane so you can hear what you've recorded.

This is exactly the same situation in analog recording (only the players are different). In a recording studio the engineer is listening to the direct signal during record... The tape machine would dutifully record everything, and the first time the tape was heard was on playback. Reason: latency

The distance between record head and playback head meant that the tape playback was several millisecond behind the *direct* signal. Just like on your computer, the tape machine had the latent signal. So the musician's headphone mixes and the engineer's control room mixes were always the direct (latency free) signal during the record process.

The signal from the analog tape machine was not heard during the record process (it remained muted, deselected actually).
Make sense?

Recording a MIDI track to your DAW. The key presses and controller movements travel to the DAW (Local Control) on the XS should be set OFF (to prevent MIDI doubling).

Yes, effectively - but as I'm using the XS Editor VST, it has no "Local Control" setting - it has the "Quick Setup - MID" buttons, which I have set to "Rec on PC" which, if I check on the Motif, set Local Control to Off.

_The MIDI track in your DAW should be routed MIDI OUT = "1-Motif XS VST-Midi In"
_This routes the MIDI data to the Editor. You will know you are successful because as you play keys on the XS the Editor' keyboard will indicate the notes you are touching.

Yes.

_The EDITOR VST > File > VSTi SETUP > you will select the driver ports for your audio interface. The MOTIF XS is on the left, use the first line Left and Right. In the center box you set your audio interface and the ports you have the XS connected to... You have the SPDIF so you have just two ports: Left and Right.

Yes, but for it to make sense to me I need to express it slightly differently: In the Audio Return Ports box, the center box, in the drop-downs I find the list of all the outputs of my audio interface. I am setting the VSTi to listen to the correct audio interface output. In this operation, I am controlling the virtual instrument in the Cubase instrument rack, not the audio interface or the Motif. (Which is hard to keep in mind because all the settings I make on the XS Editor's main window are controlling the hardware Motif). I am connecting the Audio Lane to a sound source. This was the last piece of the puzzle I figured out yesterday, but, yes, it's set. I have the spdif from the Motif coming in on the UFX's ADAT2, which is then internally routed to AES Out, so in the VSTi Setup I have set Audio Return ports L & R to AES L & R, and it works a charm.

In re-checking everything, you drew me to some other items, which seems to have solved the "issue".

First, on the Motif, under Utility > I/O > Output, I had at one time, apparently, set the L&R Gain and all the mLAN channel pair gains to +6dB. I did a matrix of experiments with every possible combination of L&R Gain, mLAN 1&2 Gain, and Output Select on the XS Editor Part 1. Using a standardized MIDI signal of 100, I measured the level on the MOTIF XS 1 Audio Lane of each combination. What I found was that in all but one case the level remained constant at -16dB. The only combinations that made any difference was having Output Select set to L&R and changing the L&R Output level on the Motif. Like this:

Output Select Set to ==>.....m1&2........................L&R

Changing Gain of
mLAN 1&2:......................no change...................no change
L&R ................................no change...................-16dB > -12dB

So, I had two mysteries:
- when Output Select is set to m1&2, why doesn't changing the gain of that output have any effect?
(and in this pure digital transfer scenario, is one of 0dB and +6dB preferable?)
- with Output Select set to m-anything, why am I hearing it on the Digital Out at all?

The second question made me look on the XS Editor at the mLAN Monitor buttons in Quick Setup. It was set to "PC Drct". I didn't think it mattered what it was set to since we weren't using the mLAN. But setting it to "St-Alone" solved the second question. Setting it to "St-Alone" produced the expected result that setting Output Select to m-whatever produced no signal - because in this mode no signal is sent to eh mLAN. I'm guessing that Digital Out provides a copy of the mLAN in stereo, as well as the main L/R analog output, so if any signal is present on mLAN, it shows up on Digital Out as well.

So that would explain my original issue. If Digital Out provides a copy of the mLAN in stereo, as well as the main L/R analog output, then having mLAN Monitor set to "PC Drct" would send the tone generator's signal to the mLAN and a copy would be sent to Digital Out. Setting Output Select to either L&R or m-anything would be receiving the same thing, just via different inputs.

What's still not clear is why changing the Output Gain of the L&R channel changes the strength of the received signal, whereas changing the Output Gain of the mLAN channels does not. But that is not really important, since I'll be using the L&R copy.

At least now I'm confident I'm receiving only one signal and there's no sound quality issues from signal-doubling.

Thank you once again for egging me on in the right direction.

Yes, effectively - but as I'm using the XS Editor VST, it has no "Local Control" setting - it has the "Quick Setup - MID" buttons, which I have set to "Rec on PC" which, if I check on the Motif, set Local Control to Off.

The Motif XS Editor VST is a 1:1 representation of the Motif XS on your computer. When "Online" any changes you make to the hardware is reflected in the software and vice versa. So, of course, there is a LOCAL CONTROL On/Off... The LOCAL CONTROL ON/OFF is found under FILE > HARDWARE UTILITY

The QUICK SETUPS make the six settings (including the condition of the Local Control parameter) but it's there in the hardware and in the software (under Hardware Utility). In general you should make the QUICK SETUP that most closely defines what you are doing at the time. REC ON PC would, indeed, set the Local Control = OFF.

Yes, but for it to make sense to me I need to express it slightly differently: In the Audio Return Ports box, the center box, in the drop-downs I find the list of all the outputs of my audio interface. I am setting the VSTi to listen to the correct audio interface output. In this operation, I am controlling the virtual instrument in the Cubase instrument rack, not the audio interface or the Motif. (Which is hard to keep in mind because all the settings I make on the XS Editor's main window are controlling the hardware Motif). I am connecting the Audio Lane to a sound source. This was the last piece of the puzzle I figured out yesterday, but, yes, it's set. I have the spdif from the Motif coming in on the UFX's ADAT2, which is then internally routed to AES Out, so in the VSTi Setup I have set Audio Return ports L & R to AES L & R, and it works a charm.

Well, not exactly. In the Audio Return Ports box, in the center are not a list of all the "outputs" of your audio interface... Those are the INPUTS to your audio interface! Huge difference.

You need to select the physical INPUT Ports to which the audio outputs of the Motif XS are connected - this is how your DAW will know where signal is coming IN from for the "Motif XS 1". Those are INPUTS listed there, not OUTPUTS. We know where the OUTPUTS of your audio interface go... They go to the computer via USB or FW and a second set of outputs feed your sound system. The VSTi SETUP is to prepare your DAW for where to look for the incoming Motif XS audio. Those are Input Ports on your audio interface. For it to make sense at all... Output of the Motif XS are connected to Inputs on your audio interface.

Motif XS Out > Audio Return Ports > DAW

AUDIO Return Ports are "INPUT" ports to your audio interface... You have connected to the ADAT 2 INPUT...

- when Output Select is set to m1&2, why doesn't changing the gain of that output have any effect?
(and in this pure digital transfer scenario, is one of 0dB and +6dB preferable?)
- with Output Select set to m-anything, why am I hearing it on the Digital Out at all?

Sorry if I wasn't clear about your two remaining "mysteries" but again, you cannot use anything dealing with the mLAN outputs m1-m14. You do not have these physical outputs connected to anything (that requires the Motif's FW option)

When you assign something to m1, m2, m3, etc. you are removing from the STEREO mix that is going to your computer via "Motif XS 1"... you only have the STEREO output of the XS connected... the top row of the VSTi SETUP window (shown below). And you are routing ONLY the LEFT and RIGHT main outputs to your audio interface... via "MOTIF XS 1"

Whether or not you are monitoring (hearing) this isolated send... will depend on your "mLAN MONITOR SETUP" - in the lower left corner of the Editor window. I mentioned that if you are hearing the audio that you have routed to an assignable (m1-m14 output) it is because you have signal routed through the "direct" path... so yes, an "mLAN MONITOR SETUP" of "PC(Drct)" would mean you are hearing the isolated signal BEFORE (pre) it going to your DAW. No mystery. That is how it is designed to work. This allows a person using a FW16E discreet OUTPUT (m1-m14) to hear (monitor) what they are doing. You will notice that even though when you route something to say m1&2, it will not be recorded in your DAW. It will simply be ignored. You do not have a signal path between m1&2 and anything in your computer, period. You simply do not have that audio bus, at all. Making sense.

(It would make sense if you were using the FW16E as your audio interface) But you are not. So you are going to set the mLAN MONITOR SETUP = stand alone. You are using an external audio interface... not mLAN.

Hope that helps clarify the last two mysteries.

Yes, all clear, and all working - thanks again.