There are a couple of USB devices that contain HD Radio and DTV tuners. I have one that's fabulous on DTV but absolutely awful, in fact, useless on HD Radio. And, until they make an iPhone with a USB port and drivers that work, such a device is hardly "portable" except that you can carry it in your pocket when it's not in use.
The HD-01 case is not too small to include a usable TV screen, unless you wanted to watch Avator on it. I have one (barely usable) Chinese product that has a 2 1/2" screen and is about the same size. It's only for MP4 video and regular FM, but suggests that size is not the issue for an evolved HD-0X.
With an AM tuner, though, you get into problems with a device this small. If there's a harmonic from any interference, an unshielded AM circuit will pick it up. In a noisy radio environment, like NYC, you wouldn't hear much besides static. In NYC, two all-news stations (WINS & WCBS) have gone onto a secondary HD channel on FM, a very smart move, as AM HD to my ear sounds worse than regular AM.
Best,
Arthur505
