batsbrew
it forces unnecessary math.
if nothing else,
more busses than necessary, could degrade the audio.
yes?

I don't believe so but if you're not sure do a null test.

A bus is a bus is a bus, whether you call it "Master" or "Submix" or "Pumpkin Pie". It's a logical summing node, that's all.
 
I can think of no good reason to have a main mix bus that feeds into a "master" bus. In analog days I'd advise against it for the noise considerations. But in the digital realm there's really no downside, other than making your routing more complicated than necessary. There's just no benefit, either.
 
My standard setup is to route drums to a drum bus, which is then sent to an Instruments bus along with every other instrument. A separate vox bus is the destination for vocals. Having separate busses for instruments and vocals allows me to automate them independently, e.g. bringing all instruments up 1-2 dB when there's no singing and then backing it down during the vocals. An alternate trick is to apply a compressor to the instruments bus, with the lead vocal as its sidechain input.
 
If you're adventurous, it can be fun to apply effects to the instruments bus. Try a tremolo plugin there, synced to the project tempo. Or a flanger (think "Itchycoo Park"). When I do that sort of thing, I sometimes route the drum bus straight into the master, leaving drums unaffected.

For me, everything (Drum Bus, Guitar Bus, Vocal Bus, etc.) goes to what I call a Mix Bus, which then goes to a Master Bus, which goes to my hardware stereo out. Typically, as I mix, I tend to end up with too high of a level when it sounds "right". By having everything going to a Mix Bus, I can simply lower the fader on it so my Master Bus is brought back to an acceptable level, yet still retains what I have decided is the "sound" I want . The only thing on my Master Bus is my final limiter. By attenuating at my Mix Bus, I am not destroying any level relationships I have set on any compressors, saturators, or whatever plugs I have elsewhere in my mix. Call me crazy but, it works for me.

bitflipper
But in the digital realm there's really no downside, other than making your routing more complicated than necessary. There's just no benefit, either.

redundant post!

+1 @Steve_Karl
 
That's why I have a Mix bus too:)
 
Bassman
 

bitflipper
 But in the digital realm there's really no downside, other than making your routing more complicated than necessary. There's just no benefit, either.

 

Everyone seems to work differently so I'll say for me, there is benefit ~~~
I don't mind complicated routing. It's all visible right there in front of me to see.

With a VUMT and brick wall on the "A" bus set to -0.1dB, and the vol. fader (in splat) set to zero, everything works fine.
Once I start changing that fader volume with an envelope, especially going into the +dB range, the brick wall is broken and doesn't contain peaks predictably below -0.1dB.
I learned this at the beginning of using X3e.

That is ~one~ of the reasons why I always have the seconday (or more sub MASTER/Summing) bus(s) before the "A".
The reason I call the first one "Conductor" is that I often use it to do long term dynamics (vol. envelope) in some pieces. I also always have a multi-band compressor on the Conductor bus.

Putting a multi-band on "A" is not as reliable because I most always fine tune the global multi-band compression near the end of the mix and then need to re-level my final output.
Easily done, once again with the gain fader on Conductor, but not reliable doing it on the "A" bus
because it often messes up the brick wall hold back at -0.1dB.

Why do I want to change the volume of everything at the same time, and in different ways throughout the piece and do it simply and quickly?
To have total control over what I'd call 'long term dynamics.'

Giving a volume swell, or decrescendo, for the whole orchestra, (or any band configuration) more range ... or less ... making that quiet section slightly less or slightly more quiet - making sure the long term peaks
( 2 bar crescendo for instance ) have the build up that I want,
the exact slope that want -
With that Conductor bus I can shape the long term dynamics quickly
and very much quicker than trying to do it one section bus at a time.

The brick wall on "A" can be hit a little bit hard and still everything goes no louder than -0.1dB for peaks and everything sounds fine as long as I don't hit it too hard.
That is NOT the case if I push the Vol. fader up on the "A" bus. It breaks the brick wall.

I can see if the Conductor gets a RED peak but no problem there. It still sounds clean.
If I want to make sure the piece has its full dynamic range, I can nudge down the gain slider on "Conductor" and let it breathe a little more making sure it might only hit 0 once or twice, or I can let it be bouncing into the +5 or +8 dB range occasionally, and everything still is ok. Maybe a bit hot for RMS ... but still ok.

Then finally if I want to fine tune my RMS output, say to as close to -11.5 dB as possible ... (Klanghelm VUMT)
... once again I just fuss with the Gain slider on the Conductor bus and it's easy as pie to get it fine tuned.

An other added BIG perk is one more stage of 4 band EQ in the ProChannel.
Using the pro channel EQ on the "A" bus messes up the brick wall.
I've also added, at times, a summing bus before the Conductor to get >>> 4 more bands of EQ,
or after the Conductor bus, in the case of one piece, where I couldn't get enough output.
I called it "Boost to A" and well, I also got >>> 4 more bands of EQ in ProChannel.

For "pop" style music it's generally the same. Fine tuning the sections of the song.
Added final EQ (or 2 or 3) for smoothing etc.

So, obviously everyone works differently.
I find using the extra busses right under "A" much more time effecient when dealing with big projects.

I'm with Dave on this.

very interesting discussion guys, thanks.

I use two. All my instrument sub-group buses (Drums, Gtr, Synths, Vox...) got to a SUBMASTER bus. I usually keep this at -6dB and is where I put all my "secret sauce" master chain fx (saturation, stereo imager, limiter, etc). This bus goes to a MASTER bus that has nothing on it but Voxengo's SPAN. 
 
I do it this way so I can route tracks straight to the MASTER that might not be part of the project. Like a reference mix for example. 

Yes very interesting stuff. I saw no use at all for the pre master buss, now after reading Steve Karl I think I'm going to try this. It might be what I WAS looking for.
It has always been the issue for me .
You get the mix sounding perfect only to find your waay to close to danger in the low and low mid's.
You end up in an endless cycle of adding EQ to tracks ( or busses) and pulling faders down and trashing what you had happening. So you reach for a  limiter and now your dynamics are squashed... be nice to control this at the Buss stage.  
I was going to try setting the LP 64 Multi band to have narrower frequency ranges for only the lower frequencies and let the Hi mid, Hi's alone.