The bottom line is you went from xlr> 1/8" ----these 1/8 inch plug can be given a mono feed and you -not know until you get home.
Anyway, going from XLR > XLR ---will usually allow you to plug into and opening in the bacK of the soundboard--- and allow you to grab stereo channels, you will then need to turn a Grace Desing V3 down between 0-5 dbs. The board will seem to give you very hot levels, because the XLR ins on the back of the V3 are generally for mics, just turn off phantom power, and the signal you received will be very hot, at pro-signal rather than consumer signal.
Not sure if any of the above is relevant or even correct...no V3 mentioned by the poster...and if you want to correctly interface a pro-level (XLR) output with a Lunatec V3....RTFM!
From the V3 manual...
The analog inputs can also be used as consumer line level inputs or, with an internal jumper change, as professional level line inputs. See the jumper configuration section of this manual for more details.
Back to the point at hand:
To be clear - you seem to have done everything right...its just that the mix only contains the instruments that needed re-enforcement.
Double check for RCA outs on the board...they are your best bet...How are you going XLR > 1/8 ? - While this CAN work - you can also get burned by too hot a signal coming from the board. XLR outputs reference a +4db signal - consumer 1/8 and RCA reference a -10db signal...big difference.
3 ways to go here:
1 - Just record the room with mics.
2 - Ask the soundman if he has an extra set of
AUX or
effects sends - he can create a separate mix form those controls - it will be mono, but will sound worlds better if done right. (also this will probably be an unbalanced signal - good since you are using unbalanced ins) You might need a splitter - since there will probably be only 1 output.
3 On stage matrix - you will need a small cheapie mixer for this. Take inventory of your last recording, note what
IS in the mix. Now place your mics on-stage accordingly - sounds like the soundboard mix you did get would be excellent for creating a matrix. If you dont have enough cable, ask the soundman if he has some extra snake channels. Get some closed ear headphones - get the soundboard in the mix and then bring in the stage mics to taste...usually just enough to keep the vocals properly above the mics...