Now that I have a PocketNC, the first thing I noticed was that I had a problem with noise volume. The air compressor Pocket NC recommends is described as “quiet and durable”. I can maybe believe the durable part, but quiet I have a harder time believing.

I’m running the machine in my home office and I measured the compressor at upwards of 85dB. That’s about the same as a bulldozer. Despite me adding some vibration damping padding, it also did a pretty good job shaking the whole house when in operation.
Since there is no real point in having a mill I can’t run because its air accessory is too loud, I replaced it with a “quiet” compressor from California Air Tools — the 8010SPC. Granted, no compressor is going to be silent, but this does a pretty good job. In the office it is totally manageable. If you close the office door, it is barely audible outside in the rest of the house.
While only about twice the cost of the Grainger unit, the bigger downside is its size and weight. Clocking in at around 120lb, it is a beast. Amazon reviews were nothing but shipping damage, so I had mine delivered to the local Home Depot at which it arrived seemingly unharmed, although with somewhat unorthodox packaging. There was just a 5 sided box dropped on top of it, with the bottom caster wheels exposed out the bottom.
The next steps here are to build a table that the compressor can sit under, and the Pocket NC can sit on top of. While running, the compressor is relatively vibration free, but it makes a pretty big kick every time it shuts off and a minor kick when it turns on. It doesn’t seem to bother the Pocket NC that much, but it probably isn’t a good thing generally.