I bought this:
https://www.sweetwater.com/store/detail/Mix5
I feel silly for asking how to connect it because there's not much to it and it looks as though it should be self-evident. 
 
The idea is to give the vocalist complete control over the level he hears, without changing the mix. I have the original MOTU Traveler (not the MK II) and theoretically it's possible to control the vocal level using the CueMix software that goes with the Traveler.
Everyone on this forum told me to get hardware instead, so I did. Now I don't know what to do with it.
Anyone?
 
Thanks - rev

Route the submix to the board and Vocal feed to the other channel.
It kind of tough because this board is small and only allows level control of 3 tracks. It is essentially a 5 track but 2 channels are stereo.

I use the Mix 8 just for my cue mixing. 
 
My system looks like this: 
 
6i6 output 1/2 go to studio monitors
6i6 output 3/4 go to ch 5/6 of the Mix 8 
My Joe Meek pre amp has 2 outputs so one goes to input 3 or my 6i6 the second to ch 2 of the mix 8. 
I then have my guitar amp using a second mike in ch 1 and my old drum machine in ch 3/4
 
What you could do is somehow split the vocal mike into 2 sends like I have. One to the Mix 5 and one to your interface. This would require a proper balanced splitter, do not use a Y cable. 
 
Or the other way would be use the Mixer as your Vocal pre amp and output from the Mix 5 to your interface using a Line input. Then the return from your interface ( output 3/4) would go to the TAPE input and only depress the "to Phones" button,, don't press the Mains or it will loop back to the daw. This would be the easiest but not sure if the Mackie pre's would be better than your Motu's. You'll have to sort that one out. Do  a listening test. 

I forgot to subscribe to the thread so I wasn't notified and I thought nobody loved me. :) Thanks for the replies!
 
Chucke:
>Route the submix to the board and Vocal feed to the other channel.
That should be OK, stereo submix and mono vocal, with a whole stereo channel left over. I was fooled by the '5' when it's really a '3'. Marketing is just Sales with a degree...
 
I forgot to mention, I have a condenser mic and I have 48 volts phantom power on the MOTU - but no phantom power on the Mix 5 unless that's the Gain control. (?)
 
Cactus:
>Or the other way would be use the Mixer as your Vocal preamp and output from the Mix 5 to your interface 
That looks like another viable way to go but I don't want anything to loopback or feedback even if it means you have to press a button to cause it, because that can happen by accident.
 
>not sure if the Mackie pre's would be better than your Motu's.
I think the MOTU must be better all round, it was expensive even when it was trailing edge but the Mix 5 was about $15.
 
>What you could do is somehow split the vocal mike into 2 sends like I have. 
The CueMix software is supposed to be able to achieve that and I would have gone that way if it worked (or If I'd understood it and got it right). In the end, turning a physical knob seemed easier.
 
The INs on this thing are marked Bal/Unbal - which is it!?
Also it has no ON/OFF switch, looks like you have to pull out the AC adapter. You get what you pay for.
 
I just found a manual online, nothing came in the box. I haven't opened the pdf yet, it might only be two pages long.
 

If I understand you correctly, then what you have won't do what you require.
 
What you need is the Behringer Headphone amplifier MA400
 
http://www.musictri.be/Categories/Behringer/Signal-Processors/Headphone-Amplifiers/MA400/p/P0491
 
It will allow you to adjust the mic level in the headphone while not affecting the level going to your DAW, which you adjust in the normal way. The monitor level can also be adjusted for a convenient balance.
Because the mic passes through, it will accept phantom power from your interface. However, it still needs power to operate the headphone amp.
 
Once your singers learn to operate it they'll love it.
Check it out.
 
 
 
 
 

I guess I should have looked up your interface first. I assumed it had limited outputs.Seems you would not even need the little mixer other than a localized level control for the Talent sitting across a room. 
 
So looks like all your going to need is to send both the vocal and the playback out to the MIx 5 using separate outputs from the Motu. Then the Talent can mix those as desired. Yes many headphone amps could also do this same trick, some use a stereo signal and mix it to mono so you send the vocals on left and DAW play back on right and blend them at the headphone amp.