Kanex adapter takes Mini DisplayPort video, USB audio to HDMI

Apple’s new MacBooks and Mac minis come with snazzy Mini DisplayPort connectors, but if you want to hook one up to your HDTV via its HDMI port, Apple can’t help—it doesn’t sell an adapter. There are a bunch of other Mini DisplayPort-to-HDMI adapters out there, but they don’t let you feed audio across the HDMI connection.

I recently bought a flat-panel TV for my bedroom, and so far as I can tell, it will only play back HDMI-based audio with an HDMI-based picture. Using an adapter like Kanex’s $17 Mini Displayport to HDMI Adapter, I could watch live streaming Wimbledon matches on my flat-screen TV, right from my MacBook Air. But I was left to listen to the match via the Air’s tinny speaker or an external speaker I connected directly to the Air’s headphone jack. Not ideal.

But Kanex has done itself one better with its new $40 Mini DisplayPort to HDMI Adapter with Audio, due in August, which includes not just a Mini DisplayPort plug but also a USB plug. The USB port grabs your Mac’s audio—I had to launch System Preferences and choose USB Audio as the output device — and sends it over HDMI along with the video from your Mini DisplayPort connection. With the new adapter, I was able to play back both video and audio on my big-screen TV direct from my laptop. (And it would also work great from a Mac mini being set up as a home-theater PC.)

The only issue with this adapter: It doesn’t send digital audio over the connection, only analog. As a result, you won’t be able to transmit Dolby Digital or DTS data, only analog stereo audio. But for my flat-screen purposes, stereo audio is just fine. And it fixes the inflexibility of my new TV set. Great news all around.

[Correction: This article misstaked Kanex’s corporate relationship to another brand. We have edited the article to remove that connection. – 7/31/09, 12 p.m. PT]