<div class="mask-synth"></div>

.mask-synth {
  background: -webkit-cross-fade( url(https://s3-us-west-2.amazonaws.com/s.cdpn.io/381167/duotone_transparent.png) ,url(https://s3-us-west-2.amazonaws.com/s.cdpn.io/381167/duotone_transparent2.png) , 10% );
  background-size: cover;
  width: 100%;
  height: 450px;
}

.mask-synth:before {
  content:"";
  position: absolute;
  background: linear-gradient(rgba(204, 51, 153, 0.8), rgba(255, 204, 102, 0.6));
  width: 100%;
  height: 450px;
}