Hi, so I know that in a post fader send the level of that aux track basically slaves to the level of the corresponding audio track(s) being sent to it, so if I send say a snare to a reverb aux then anytime I adjust the fader on the snare audio track that reverb aux level will mirror the level change.

So with that in mind what I'm trying to understand now is, say you have 10 drum tracks all being sent post fader to a single aux w/ a reverb on it. Considering that the level on this reverb aux is supposed to follow any level changes made on any of the corresponding audio tracks being sent to it; if you're sending 10 drum tracks to a single aux verb track, how does the aux track level slave to each of those 10 tracks individually? Like, those 10 drum tracks are not going to all be at the same level, so if I turn the kick track down say -5 then that reverb aux will follow that, right? But then say I turn the snare track up +6, doesn't the aux track then have to follow that, too? I guess what I'm asking is, how does this reverb aux level, which is receiving 10 drum tracks via post fader, slave to all 10 drum track levels, all of which are and can be set differently, at once? How does a single aux track level obey the level changes of 10 separate drum tracks being sent to it? It seems if I turn the snare track up then the aux track turns up with it, but then if I turn the hi hat down then the aux track then turns down for THAT track. Probably a dumb question, but I just want to make sure I understand this right. Thanks again!

The confusion is that you're thinking in terms of a fader going up and down on the bus/aux, but its gain/volume isn't changing. What's changing is the amount of signal being sent to it by each of the drums tracks, which naturally follows their volume faders when the send is post-fader.

bitflipper
The confusion is that you're thinking in terms of a fader going up and down on the bus/aux, but its gain/volume isn't changing. What's changing is the amount of signal being sent to it by each of the drums tracks, which naturally follows their volume faders when the send is post-fader.

Ah so in post fader it's the per track send level that's slaving/changing w/ the track's volume fader and not the level on the aux track itself? I'm not at my daw now, but is it correct that there's no visual representation of this, i.e. the per track send level knob doesn't visibly change w/ the track's fader when in post fader, but just happens in the background? Thanks man

Correct, there no visual indication. You can only see what's happening by placing a meter on the bus and isolating each track. That's usually not necessary because the ratios of the sends are equal to the ratios of the normal mix. At least until you move the Send fader, anyway. It's an adjustment normally made by ear, sometimes requiring you to solo the bus to determine exactly what's hitting it.
 
On a related tangent, also bear in mind that the panning of sends may or may not follow the track's pan. The default, I believe, is to follow the track. Obviously, changing the pan of the send will also impact what the aux hears.

Another thing that I found out the hard way is when using sends all of that is cumulative in the total mix. IOW if you had a nice balance before the sends, you might need to revisit this post send. On especially lush reverb sends I sometimes roll ff some of the the low end or it builds up too much. Depending on the plugins in the send you might need to use some control strategies to tame things back down.

Awesome thanks for the explanation guys. Now to wrap my head around compression.

Starise
Another thing that I found out the hard way is when using sends all of that is cumulative in the total mix. IOW if you had a nice balance before the sends, you might need to revisit this post send. On especially lush reverb sends I sometimes roll ff some of the the low end or it builds up too much. Depending on the plugins in the send you might need to use some control strategies to tame things back down.

One thing I started a while back was to insert a HPF before the reverb to kill the mud from being propagated, followed by a LPF after the verb to remove unwanted highs
 
This can make for a much cleaner mix

Bristol_Jonesey

Starise
Another thing that I found out the hard way is when using sends all of that is cumulative in the total mix. IOW if you had a nice balance before the sends, you might need to revisit this post send. On especially lush reverb sends I sometimes roll ff some of the the low end or it builds up too much. Depending on the plugins in the send you might need to use some control strategies to tame things back down.

One thing I started a while back was to insert a HPF before the reverb to kill the mud from being propagated, followed by a LPF after the verb to remove unwanted highs
 
This can make for a much cleaner mix

I do something similar, but sometimes play with the position of the EQ just a little.
I noticed that if I don't put an EQ before the reverb, but use the HPF after (along with a LPF), depending on the material, the reverb sounds more natural.
doesn't work in every situation but is effective at times.