I've found these cheap adapters tend to stop working after a couple of grows. I resorted to using an old power supply from a pc, great thing about that is it has a fan in it so I rigged that up as an intake then it powers my internal airflow. No wiring required.
Computer fans can have pretty high airflow for their size and noise.
However if you have old crappy fans then they won't move enough air and will be noisey, I've always used new fans.