I haven't had any air issues in my drains. Once the air in my lines flushes it's done and dead quiet. And that's running 1-1/2" plumbing with an Eheim 1262.
My return line is 1" and splits into 2 x 3/4" loclines.
My main drain is below the level in the sump(submerged to keep a siphon), and my emerg in above to alert me with splashing noises ... like I'm ever around to hear it
Once my main flushes itself, it runs dead silent. My tank is surprisingly quiet.
I've worked on things to make it quiet with padding and such.
Anyone who's been here buying corals can tell you, and there's been dozens of peeps.
Anyway ...
Don't worry about drainage noise as long as you set up your drains properly.
We can help you work on that later.
Get your tank in place and we'll work on the other stuff later.