I have written a little article which I posted over on the Presonus forum. The topic of gain staging came up and I responded with this article. It of course applies to any DAW.
 
Note:  In Sonar the rms meters are showing a further 3 dB value down from the industry standard which is showing the very peak of a continuous sine wave as being the actual ref level.  Not a point 3 db down from that.  It is actually technically correct as rms is 3 db down from peak in normal electronics circles.  But once you start using third party VU meter plugins inside your DAW they will be showing the correct readings and scale defections while calibrating etc..
 
 
https://drive.google.com/file/d/0B_2Jb7O_b5BkODRTMXNjX29IaEE/view?usp=sharing
 
The above is a link to my Google drive which will link you directly to the article.
 

Thanks Jeff. I could do with some clarity on this subject right now. 
 
 

Thanks, it is a pleasure. I do mention Personus VU meters in this article but only because it was originally written for a Studio One user in mind.  We have some free VU meters over there which can be pressed into service in this role. They are not perfect for a few reasons but effective in keeping an eye on rms levels everywhere in your production.
 
There are of course free VU meter plugins out there and they are OK as well.  While they will show a ref level sine wave accurately,  they often don't have the best ballistics and that is where a quality VU type plugin comes into play.
 
You guys may have some Pro Channel modules too which have VU metering on them.  Just be aware of what any reference levels might be with any built in VU meter.  Test with some signals to find out! What ref level are they showing you?  
 
It is nice to have some nice VU plug-ins on hand to simply insert wherever you need to know what the signal rms level is at any point in your production.  Klanghelm VUMT comes to mind. Very cheap and exceptional.  It has now had a total refresh and available as V2 and also a deluxe version of V2 is also available for not much more. 

I haven't read your article Jeff, but to me there is no need to worry about the real world and real world meters if you are staying in the box...I have a simple formula for using and setting the meters in Sonar, and it seems to work. This is all tracks start roughly at -18rms then as the mix takes shape, the tracks which need to be at the front of the mix are lifted closer to 0db rms. Final master Lufs the new standard is always within range, as is the K14meters...this is 0 to +4.
 
From my research, and apparently I am a qualified researcher (hmm Wednesday next week lol), the issue seems to be we have been misunderstanding the medium of both analogue and digital. Neither of which are perfect in regards to being a storage and transmission medium, both have desirable aesthetics. This is one the of dichotomies of the avant-gardes'...they introduce new materials and mediums into the art cannon, but reject the formalist art tradition, which means we don't have a great understanding of the digitized medium. :)
 
The real problem is, and the only reason why you would need to do all the real world calibrations, is if you are going in and out of the box all the time. Something that I now believe is a big no no! Proper gain staging in the box is still paramount, but the digitized medium requires a different mind set to the one originally taught in the early noughties. This is particularly true if you are using the analogue emulation aesthetic. Not so much, if you're using the digitzed medium as a storage only medium ;). What I think analogue audio engineers need to understand is, if they're going to be making an analogue product...then the signal chain has to be quality from tracking to storage to distribution. Whereas if you're making a digital product, then the signal chain has to be lacking character as much as possible. This allows the digital engineer to put the flavour back in as he or she sees fit. What we need to start to do is, separate the sonik creations into digital and analogue...much like a painting...I'm painting an analogue sonik work or I'm painting a digital sonik work. I've actually written a paper for an academic journal (waiting for the outcome) on the topic of the ethereal material of sound, so it might sound funny to use the term 'paint', but sound is a material albeit an etheareal one, and one that can be painted or sculptured. This will be even more apparent when and if augmented reality become the defacto input device for our computers...think about it virtual gloves will allow us to shape sound in our hands and there is even tech coming which will allow us to feel this sound as we shape it in our hands.
 
Ben

Thanks Jeff. I always appreciate your insight.

I feel there are some differences in regards to gain staging in the digital world but there are also some concepts that carry over rather well from our previous eras. Using VU meters to keep an eye on rms levels is one of them.
 
The type of calibration I am referring to is the type staying all ITB but just making sure all your VU meters agree on the chosen reference.  
 
Going In and OUT of the box to external gear also requires a different form of calibration where a certain ref level will equal an actual AC voltage present at the outputs from your interface.  The interface itself determines what these voltages will be.  But important though.  If you are wanting +4 dBu to leave your interface, you need to know what ref level you have to be at in order to achieve it.
 
 

Thanks Jeff! It's starting to sink in. I've been thinking about metering for some time now, just haven't gotten around to it. Now I see the value of using them in all those in between places.
 
Very helpful.

Since "Many plugins are calibrated to work at -18." If I have a few guitar tracks that all go to a "Guitar BUS", and I want to use the PC4K Bus Compressor on that guitar bus, should I trim the bus so that the signal is entering the compressor at -18 ???                                                                                                                                                                                                                   Jeff, Thank You for the article!!! It has been very helpful !!

Only if you are working at an rms ref level other than -18 = 0 dB VU.  Then it might be a good idea to adjust signal levels going in and out of some plugins relative to the ref level you are working at.
 
That brings us to the next thing. What rms ref level are you working at?  One simple way to find out  (and I suspect many others may not actually know what rms level they are working at) is to insert a Klanghelm VU meter over a nice mix that you have done. But a pre mastered mix though.  Simply keep adjusting the Cal level control until the VU needle rises and reaches and hovers around 0 dB most of the time.  There will be a point where the needle does this. Then note your Cal level and that is the rms level of your mix.
 
(Note: the ballistic of the meter is important here. A cheap or free VU meter plugin won't move properly and it may swing more wildly and therefore it may reach 0 dB VU at a lower cal level than what is really happening. The Klanghelm meter while not as perfect as real VU meters, is very close)
 
The reason many have no idea about rms and what rms ref levels that are operating at is because we have been too pre occupied with peak meters.  But they tell you nothing about the real stuff e.g. the rms levels underneath that peak.  Peak metering is critical in the fast transient sounds for sure. We need them.  We need both.  A VU meter takes 300 mS to reach 0 dB VU so any fast transient is not even going to move the VU needle.  But for a great majority of signals, the rms indicator is fine.

THANKS Jeff !!