Ideally - you would just use the band/clubs stage snake...there are likely some extra channels...set your stuff up back at the board...get the two channels from the snake - and go!
in that scenario, unless you put mics onstage, you will STILL need a delay unit
I thought that the onstage setup was implied. Maybe some dont know what a "snake" is...
The Snake is large box with XLR inputs that is located on the stage...all the mics used to mic the band are plugged into the snake...
The cable from the snake is very long...and goes back to wherever the soundboard is. Set your recorder up at the board.
At the end of the snake are any number of XLR males...(depending on how many channels the board has)
In most cases - there are say 24 channels - plenty for most acts. So a few channels will be free.
You set your mics up onstage...plug them into the snake...
Now - back at the soundboard(at the other end of the snake) - figure out which two channels you are using, and plug them into your preamp.
Now get the board feed and add that using whatever mixer/pre you happen to use...
ANOTHER APPROACH:
Say you cant really set up near the board -
Well - use the snake in reverse - send the board singal back through snake to the stage (ask the mix person if the have an extra monitor send)
Set up mics onstage - but under this scenario they go right into your preamp - then get the board mix from the snake and matrix away...
Variations on above -
1. - send whole board mix back through snake...you get the house mix
2. - ask about the extra monitor send - then have the soundguy add only the stuff you want in that send(instead of the whole mix) - for instance - most onstage recordings just need a little clarity added to vocals - so just have soundman add the vocals in your send...