It's probably a bit too late but here's my take. With the same issue on my hands, my research came up with the Hitachi / Metabo EC28M Ultra Quiet compressor. As it turns out, it should be arriving on my door step today. The video link below really sold me on it; extremely quiet. Under $200 and no fiddling having to adapt something from a previous life.
Edit : my new Metabo Ultra Quiet compressor just arrived. It is light, compact, and wonderfully quiet compared to any other compressor that I have used. I plan to use my for a mist system also.
One thing that I did learn along the way is that is that the decibel scale is logarithmic. So, if one item is 40 db and another is 50 db, the 50 db machine is not just 25% louder, it is 10 times louder.
According to the
Pulsar Instruments web site :
"
On the decibel scale, the quietest audible sound (perceived near total silence) is 0 dB. A sound 10 times more powerful is 10 dB. A sound 100 times more powerful than near total silence is 20 dB. A sound 1,000 times more powerful than near total silence is 30 dB, 40 dB and so on. "
This video does a good job of illustrating the noise level of this compressor :