Yeah little behringer mixers with verb at the various play stations is a treat.
Distribution to more than one mixer requires some sort of distribution but if you are the least bit commercial, this setup is vital for the performers experience and also your sanity.
 
I used some surplus distribution amps and snake cable off ebay to do it when i was taking money.
I also used high iso phones in the tracking room too.

You could always make it a routine to route everything but vocals to a single bus so you could just pull the bus level down.
 
I always have buses for drums, bass, guitars, keyboards, orch, so I can just pull several buses down quickly.  If everything except for vocals went to a single bus, it would be even quicker.

konradh:
That's very much like working with a mixed track, you can turn the whole track down at once. I'm into the idea of doing vocals in a different file because I won't have 5 or 6 plugs in the Synth Rack.
rev

@GaryMedia: I have the MA400 and the Artcessories MyMonitor. Both take 12v and I find both distort before there is enough headphone level for the vocalist to overcome what's coming in directly through bone conduction, etc.
 
@bitman: I use those Behringer Xenyx mixers with built-in FX. I tap off the audio directly after the mic preamp and send that out to RCA sockets I have mounted on the back.
 
I need to first set the trim knob (gain) to get optimum output.
 
The output from the interface returns to one of the line level channels on the Behringer mixer.
The artist can now set their own overall headphone level, their own reverb (essential to encourage shy singers to belt it out) and their own backing track level.
 
I would love to use my Mackie 1202 VLZ4. It has super quiet preamps, sockets at the back ready-fitted for tapping the preamp signal after gain and before EQ and levels, but unfortunately it has no built-in FX and that is what it's all about.

You need a proper mixing board with inputs that can be routed to BOTH the mains and to subgroup outs.
 

1. The output from the DA converter carrying the mix output from Sonar should be routed to a stereo input on the board, and route that fader to Mains Out ... Mains Out goes to the monitors and the headphone(s).  There is NO vocal in this mix.
2. The vocalist(s) mic(s) should be routed to Mains Out --AND-- routed to the Subgroup-Output which feeds the AD converter "in" which records the track(s) in Sonar.  Input Echo should be OFF.
3. Record vocals dry.  Don't RECORD reverb, EQ or compression. The reverb or whatever in the headphones to assist tonal accuracy of the singer should NOT be routed to Sonar, and should not come somehow from a Sonar plugin.  Use outboard gear or effects built into the board -- those effects are routed ONLY to the headphones.  You can always cut a boarder shorter, but you can't cut it longer.
4. Adjust the mic(s) for PROPER gain for recording.   Then leave alone. 
5. Use the fader carrying the mix output from Sonar (number 1 above) to bring the mix up or down in the headphones to make the singer happy. 
6. None of Sonar's faders need be adjusted.  You don't need to export anything.  You don't need an alternative mix.  You do need some beer because the vocalist is completely tone deaf and oblivious to the glaringly apparent fact that they cannot sing, and that you'd do the world a favor by going ahead with your plan involving a shallow grave out behind the vacant store next door to the studio.

I just got the answer from MOTU tech support. It's much simpler than most of the answers above and you DO NOT NEED any additional hardware!
 
In this example, my Sonar outputs are Analog 1/2 and I have only a mixed track to sing to in the project, and empty vocal tracks waiting to be filled.
 
1) Open CueMix and under the Phones menu, choose Analog 1/2
2) Choose Analog 1/2 from the dropdown menu found just above the CueMix master fader
3) Make sure the CueMix master fader and the CueMix vocal input fader are unmuted and turned up
 
That's it! You can now control the vocal level with a combination of moving the vocal input fader in CueMix or turning down the mixed track in Sonar. You can also patch in an external effects processor to allow singers to hear reverb as they sing that doesn't get recorded.
 
Thanks to all for all the amazing tips! I can see that additional hardware would make the reverb easier to patch in because that feature in Sonar seems to work depending on the phase of the moon. My singers don't care though, and this will definitely work for me. 
 
Thanks - rev

Hi, I am using Sonar Artiste with a Focusrite Saphire 2i2. I am having problems with the output levels, both headphone and main volume to my powered speakers. Is there a way of raising these levels within the programme please?  

Hi and welcome to the forum.
 
Please start your own thread and list you entire system spec including interface, driver etc and how you've got things set up in Artiste