At the end of February, we looked at Griffin’s Video Display Adapter, a generically named, seemingly simple $40 adapter that converted a MacBook’s Mini DisplayPort video connector into an HDMI video connector. Soon thereafter, TeleAdapt contacted us with its own alternative, the Mini DisplayPort + USB Audio to HDMI Adapter shown here, which also sells for $40—only $3 more than the virtually identical-looking version sold by Monoprice.

Unlike Griffin’s smaller adapter, the TeleAdapt part transforms both video and audio from a Mini DisplayPort-equipped MacBook computer, pulling the video signal from the Mini DisplayPort connector and stereo audio from an open USB port. The video and audio signals are then mixed together into a large, ventilated HDMI housing; once again, you supply the HDMI cable to connect this Adapter to your HDMI-ready TV set. Once the TV is connected, you can output iTunes or other video—including high-definition iTunes Store movies—directly from your computer to the TV set, though some extra steps are needed.

When we connected the TeleAdapt unit to a 720p HDTV, the connection didn’t start immediately: we had to go into the MacBook Pro’s Display settings, choose 720p output, and then choose 60Hz (NTSC) rather than 50Hz (PAL), extra steps that might confuse some users—the HDTV’s screen remained black until we picked the correct settings.

At that point, the audio wasn’t working, so we had to go to the MacBook Pro’s Sound settings, choose the Output tab, and then pick USB Sound Device. As soon as this step was completed, the MacBook Pro’s video and audio were both working on the HDTV; getting the iTunes Store HD video to play in full screen on the TV required us to use monitor mirroring, another Display option.

But after these settings were in place, audio and video were perfect going from the MacBook Pro to the HDMI-equipped HDTV. The left and right channels of audio performed correctly through the TV’s left and right speakers, and the 720p video was as clear on the TV screen as on the MacBook’s. By turning monitor mirroring off, we could use the HDTV as one display for windowed video, while using the MacBook’s screen for other content, or vice-versa. There was only one surprise: the connection worked in only one direction, so we couldn’t plug an HDMI device (the Xbox 360) into the TeleAdapt box, then the Adapter into the back of an iMac, and play the Xbox 360 on the iMac’s screen. Monoprice’s web site explicitly rules this out: “This device is not Bidirectional. It can only connect a Mini-DisplayPort source to an HDMI display. It will not work in reverse.” TeleAdapt’s page says that the Adapter supports “Mini DisplayPort 1.1a input, USB 2.0 input and HDMI1.2a output,” which doesn’t rule out bidirectional performance, but doesn’t promise it, either. (Notably, TeleAdapt’s package actually certifies HDMI 1.3b support, as well.)

Whether one or neither of these cables is right for your MacBook Mini DisplayPort output needs is up to you; Griffin’s cable is much smaller and better-suited to video-only output, offering both HDMI and DVI output solutions, while TeleAdapt’s larger, boxier cable provides clean video and audio output solely to an HDMI port for the same price, with some additional settings tweaking needed on the MacBook side. Neither includes the male HDMI cable you’ll need for your TV, and neither performed bidirectionally in our testing, but both make it possible to enjoy iTunes video content on a display larger than the one in your MacBook.