With any new audio system install, the P.A. is key: It should be geared toward the type of entertainment that will be traipsing across the stage. It must offer adequate coverage to deliver the sound all the way to the back wall. And, of course, it needs to sound good. But being able to adapt to altitude and air pressure? That’s not a requirement many installers may encounter, but for Bret Dowlen, president of Arvada, Colorado–based Dowlen Sound, this factor is paramount for the Denver area. And when he was hired on to handle the audio system install and limited acoustic treatments for the recently opened 1st Bank Center (a joint venture between AEG Live Rocky Mountai...