Can anyone confirm signal path?

I bought this small box to use as a vocal submix device that would enable the singer to hear any mix he wants to sing to. There doesn't appear to be a manual and I'm not sure of the signal path.
 
Here's what I think is supposed to happen:

• Mic in, top left
• music in from audio interface via CD IN
• monitor out to headphone amp

So now I have a mix of music and vocals and I'm hearing it via the mon out. But how do I get vocals only back to the audio interface? Have I bought the wrong thing?
 
http://www.steren.com.mx/mezcladora-usb-portatil-de-3-canales.html
 
Thanks - rev

I've already bought it (long story). I can't find an English site (Steren is Mexican) and Translate this Page doesn't work but this link might have a better picture.
 
https://translate.google....atil-de-3-canales.html

Without a circuit diagram I don't think one can know how the signal flow is on that device.  

Hey rev,
Specs (in english) are listed on this website if it helps.
http://www.newteksupply.com/Steren-USB-3-Channel-Portable-Audio-Mixer_p_19157.html
HeyDan

Translates fine in IE with Bing. Looks like a normal USB mixer to me. I would guess output is USB to your computer which should see it as an interface.
 
Portable 3-channel USB mixer
It transmits and mix audio from your PC or laptop!
USB input for direct audio from a computer transfer
Cannon/6.3 mm microphone entry
2 AUX RCA inputs for audio players
Treble and bass graphic EQ per channel
(Left, right) channel balance control
3.5 mm stereo and RCA outputs
You can connect headphones by AUX 3.5 mm for monitoring
USB type B entry works also for feeding  <<<--- this probably means DC power

John
 
Its a Talent device and can be had for $39.95 US. 

the elusive 'talent' button, and for onlyh $39.95, who'd have thought it would be so cheap? . . . i think there will be a run on this

Just so we can all get past the price, the peso is around 20:1 which means I paid roughly $74 US. OK?
 
It's described as a USB mixer but there is no USB input. The only USB is on the back and it's for power. Assuming you could convert USB input to RCA jacks, then it would work but Mexico doesn't care much about misleading advertising. The reason there's no manual or signal flow chart is because it's not necessary, it's a Karaoke device whose function is obvious (to me now). Yes, I've figured that out. It only does this:

• Music in, voice in, a mix of both out.

The rest is just there to accept different sources for the music, the buttons direct the output to either monitor or main. The questions I had in the store (in Spanish) all seemed to be answered adequately.

• Does it mix vocals and music? Yes.
• For recording? Yes. (this is where I should have been more specific)
• Can you vary levels in the output? Yes (etc)

The dude wasn't wrong but obviously he didn't understand the desired application.  
 
I live in Mexico and it's very difficult to get stuff from the US. Most US vendors won't accept Mexican credit cards, they must think I'm laundering my $74 bucks. If you can get something shipped, Mexico wants 16% tax and another 16% import duty so you might not save any money, especially after shipping. It can all be fudged, some vendors will even change the amount on the receipt to help you out but unless you have a friend coming down to visit, it's can be a lengthy fiasco. 
 
I may be able to trade up at the same store or get half back from a DJ type person.

Looks like a behringer unit.