Amarista went 3-for-5 and Yonder Alonso and Nick Hundley both had two RBI for the Padres, who won the first two games of the three-game visit to Dodger Stadium.
San Diego outhit the Dodgers 15-4.
Jason Marquis (1-1) earned the win by holding the Dodgers to one run on three hits over 7 1/3 innings. Marquis set down 12 batters in a row at one point.
Mark Ellis got the Dodgers on the scoreboard with a sacrifice fly in the third inning after San Diego had built a 5-0 lead.