A quiet compressor?

Screw compressors are not really quiet. We have a half dozen of them at work and they are quite loud. They are made for high volume continuous duty, not really harry homeowner equipment.
I did a lot of shopping around and ended up getting a Quincy. Buy one of these and it will last your lifetime. The key to quiet is the low RPM (1750). I had mine in the garage for a year but it put out too much heat. I built a compressor building attached to the outside of my garage and its perfect. Its been out there for 2 years and its the best thing I ever did.
When im in the garage I can just barely hear the compressor running.
At 22.6 CFM this thing is no slouch. It will run any air tool and I do a ton of sandblasting with it.
Quincy QT-7.5 Splash Lubricated Reciprocating Air Compressor with MAX Package — 7.5 HP, 230 Volt, 1 Phase, 80 Gallon Vertical, Model# 271C80VCBM | Northern Tool + Equipment
Other Quincys
Quincy Compressor | Air Tools + Compressors | Northern Tool + Equipment

Get a compressor with more cfm than you think you will need. Also watch out for cfm ratings at 90 psi. Many of the cheaper compressors list their cfm @ 90 to make them look better than they are. My compressor is rated at 175 psi but I only run it at 125.