Hi myker,
please-never use Y-cables in such type of setup!
You are asking for a lot of trouble when doing it (e.g. if one wire breaks you will get your lines unbalanced;if there is a short you´ll have it on both ends of Y-cable etc.).
Best way is to get these signals isolated from each other.Normally this is done by a transformer.
If using a passive splitter you have to run one parallel-o/p to the Input of the splitter.Connect the mixer or mic-pres with the shortest cables here to provide phantom (+48v).On the other splitter outputs you connect the other destinations (isolated then...).
For example a classic set is:
a) split-point on stage (in your case a box with 16 channels input XLR female to one direct(parallel) output XLR male and one or two(more usual) transformer outputs XLR male=1:3-split)
b)Mic-snake from stage connected to the inputs of the split-box
c)one (isolated) line per signal connected to f.o.h.
d)one(isolated) line per signal connected to your recording system (with mic-pres or mixer in front of it of course
e)one direct (paralleled) line to-let´s say-monitor-desk;switch phantom on here if needed and leave the phantoms on the other connected mixers/pres off.You can not transport +48v thru a transformer!
Now you´re done.
Best to connect the "phantom-supplier" to the direct-output of the splitbox is always the one which is closest to the stage-in this case a monitor-desk;but this can be your recording-stuff too-depends on cable-length between split and destinations.
This was a short trip on how to split signals in a real life situation.
There are more possibilities (active splitting-can be very expensive but is best in analog-audio!) but this is the simplest and cheapest way to go.
Another possibility is to record from the direct outputs of the f.o.h.-mixer-but this makes only sense if the direct out on it is pre-fader and even pre eq/inserts-otherwise you´ll record everything what the f.o.h.-guy is doing and therefore will not be able to "fix it in the mix" afterwards!!!
And even if direct outs are pre-everything you still depend on the gains of the console (do you trust this guy :-\).
I hope this was a little help for you-splitting signals can become very complex in a live situation (more split-outputs;running systems from different mains;troubleshooting things while having stress etc.).
It´s up to you now,i must go to bed...
Excuse my bad english-i´m trying to improve this (talking is o.k. for me but writing-hmmmmmm....).
Have a nice day!
Udo.