The e isn't silent. Klasse is a german acolade, akin to great or wonderfull.
"Classy" isn't correct pronounciation, but for Americans, it's close enough. "Class-eh" is closer. The a isn't that hard, it's softer, like in the word "care". Mmm, if you don't goober it, "Cless-eh" would be very close. Accent is on the first syllable, "Cless-eh".