I have two in the basement, each controlled by a separate wall-mounted humidistat that I installed. Humidity control is rather precise. One advantage of that control is that the unit runs only when actually needed- no run=no noise. Since the unit drains into a floor drain system, I set it on a foam rubber pad to lessen the noise. It helped a little.

I built an acoustical ceiling tile box that goes around a dehumidifier... lessens noise quite a bit. Thought about making it its own little drywall box with a nice filter someday.

Enclosing the dehumidifier would no doubt lessen the noise. But the enclosure would have to be very carefully designed and fabricated so as not to interfere with free air movement to-and-away-from the unit. If the enclosure permitted the air to move around within the enclosure and just recirculate directly through the unit, it could defeat the whole purpose of the dehumidifier.