With this new adapter, newer Macs with Mini DisplayPorts can now be connected to an HD source and have digital audio be outputted through the adapter. There have been other adapters, but some didn't offer audio output, which is one of the big selling points of the Kanex device.
The gadget can turn a DisplayPort video signal into a 1080p signal over HDMI, and integrate either digital or analog audio into the mix. In other words, you full full A/V with just one cable.

The Kanex adapter is USB powered, so there's no power supply to take up desk space. And you don't have to worry about multiple cables, such as a 3.5mm to RCA cable, in order to output audio from your Mac. The adapter supports: HDMI 165MHz/1.65Gbps per channel (4.95 Gbps all channel) bandwidth; HDMI resolution of up to 1080p; HDMI 8 bit per channel (24 bit all channel) deep color; uncompressed audio such as LPCM; and compressed audio such as DTS Digital, Dolby Digital (including DTS-HD and Dolby True HD.

Hooking it up is a breeze:

1) Connect the HDMI output of the adapter to an HD display using the HDMI M/M cable.
2) Connect the special fiber cable to the adapter and Mac.
3) Plug the Mini DisplayPort cable of the adapter into the Mac.
4) Plug the USB cable of the adapter into your Mac.
Go to the Mac OS X System Preferences app and click “System Preferences.”
Click “Sound” on the dialog box of “System Preferences." Click “Digital Out“ on the dialog box of “Sound”, then the adapter can get digital sound from the Mac.
Click “Displays” on the dialog box of “System Preferences,” click “Arrangement” on the dialog box of “Color LCD,” and tick off “Mirror Display.
8) Select your preference resolution on the dialog box of “MDP Adapter” and finish all the setting steps.

Volia! You're good to go.

At $69.99, the Kanex Mini DisplayPort to HDMI adapter isn't the cheapest adapter you'll ever buy. But it's one of the cleanest, simplest ways to hook your Mac up to HDTVs or HDMI devices.

Macsimum rating: 10 out of 10