Boom is a volume booster app for your Mac.
It increases the system audio volume to produce better-quality audio from the built-in speakers. The system-wide graphic equalizer can further enhance your Mac’s audio quality.
Boom won the Macworld Best of Show award for its simplicity, elegance and well-crafted user interface. It is priced at $6.99 and can be purchased from the Global Delight Online Store or through the Mac App Store. There’s also a free 7-day trial.