If you felt a low grumbling sound somewhere between your breastplate and bowels last night, a sonic force emanating from the direction of North Virginia, do not be alarmed. It was in fact a military exercise. The U.S. Army Band “Pershing’s Own” was performing tuba. A lot of tuba. Last night saw the conclusion of the 2009 Annual Tuba-Euphonium Conference, featuring a big brass–centric concert by “Pershing’s Own.” Naturally, the night started with a John…