multistage op amp vs dcdc converter

I need to amplify a 5v peak to peak square wave to a 45v peak to peak square wave. what is the advantages/disadvantages of the two approaches 1) using a multistage op amp setup 2) supplying an op amp with the necessary voltage by means of a dcdc converter

is one method more power efficient than the other?

nevermind, made a basic error in my assumption