CREATE TABLE table_66732 ("# Tubes" TEXT, "Converter" TEXT, "Det/Pre-amp" TEXT, "Audio Amp" TEXT, "Rectifier" TEXT)

Name the # tubes with audio amp of x
SELECT "# Tubes" FROM table_66732 WHERE "Audio Amp" = 'x'
SELECT "# Tubes" FROM "table_66732" WHERE "Audio Amp" = 'x'