Lava is "buzzing" or making some other sound when powered "ON".
Verify that the mounting bolts are fully tightened on the rail.
If not: Tighten them until snug.
If bolts are tight: Look behind the LAVA and check to see if the rail is touching the rear of the enclosure. If it is, that is the cause of the sound.
Solution: Take some felt, and attach it in between the rail and enclosure. Units received from Etherma during 2013 will be shipped with felt on the mounting rails.