Remember the original iSub, Harman Kardon’s subwoofer designed specifically for the iMac? That’s the inspiration behind Twelve South’s BassJump subwoofer, which works with Macs and is designed to complement their built-in speakers. Now Twelve South has improved the software included with the BassJump to improve compatibility and sound quality. A free upgrade for existing BassJump owners, BassJump has been rebranded as BassJump 2. It costs $69.99.

Designed to complement the sleek, minimalist lines of Apple products, the BassJump enclosure is made out of extruded aluminum with a metal weave grille 6.57 inches on a side and 3.75 inches tall. Inside is a 77 mm subwoofer speaker cone that outputs up to 80 dB. It’s USB powered, so no external AC adapter is required, making it a good portable solution for users looking to get improved audio out of their MacBook Air or MacBook Pro. A 30-inch USB cable is included.

While it’s billed as BassJump 2, the hardware hasn’t changed from the original – what’s new is the software (which can be downloaded from the Web site, if you already have the BassJump). The new software expands compatibility with new models and provides an additional 8 dB.

The BassJump 2 setup is now compatible with the MacBook Pro, original MacBook, MacBook Air, iMac, Apple Cinema Display with built-in speakers or Apple Thunderbolt Display.