[DupleMeter]

Another thought - While compression can be a "technical" thing, like a tool to help reach a specific integrated loudness target, it should first be a "feel" thing. It has to be musical. It has to help the track breathe.

I'm training a new assistant at the studio & we had a long discussion about compression the other day. What helped her understand the benefit of compression in mastering or on a master bus or stem submix was when I told her to think about compression, not so much in the technical sense of reducing peaks to allows the overall volume to be increased, but to think about it as taking all those sounds in the mix and squeezing them a little closer together. That's the idea behind the "glue" compression everyone talks about. You're forcing the sounds to cozy up to each other. The audio equivalent of a Gaussian blur in Photoshop. A very slight blur just reduces the "separateness" of all the elements.

I don't know a single Grammy winning mixer who doesn't compress their 2-bus, and I know a few of them. This is the reason they do. Not for the technical, but for a musicality of it's feel, and that's how they describe it and talk about it.

So, regardless of how you want to approach the loudness standards, there is a ton of benefit in adding some compression with a really nice sounding compressor.