Thanks very much, Funkedup and Skurj, for your help. Unfortunately, my audio and mike input advanced controls remain grayed out no matter how I approach them.
Apparently my sound is not as configurable as the SoundBlaster cards. I have 6-channel audio on my Dragon Ultra Soyo motherboard, and no audio software other than XP.
Maybe the microphone boost got overlooked in all the 6-channel heroics? For the time being it's another computer mystery that hopefully will someday serendipitously yield a solution.
Meanwhile, volume is fine when I hold the lapel mike two inches from my mouth. So my choices are (1) fly one-handed, (2) clamp the mike on my collar and shout, or (3) fly and not talk. Much like the typing alternatives while flying.