A full house, lively conversations and outbursts of laughter light up this corner of Barrio Presidio, otherwise darkened for the weekend. Everyone's drinking fine whiskey, or planning a drink with knowledgeable bartenders. Whiskey is serious business, here. The piano-bar ambience, held down by a Rosano brother, Howe Gelb or another secret piano master, may not feature show tunes, but it sure feels like Clark Street.