DAB radio is not a liberating technology. Here's why:
AM/FM radio receivers:
DAB radio is much more intricate to produce and receive. DAB radio signals are produced by taking a whole selection of channels (e.g. the entire BBC output), digitally encoding them, and mixing all these channels into a single digital signal which is then broadcast on multiple frequencies at once. In order to receive DAB radio, a unit needs to listen to all (or most) of these frequencies in order to get a clear digital signal, then "demux" (separate out) the various channels bound up in the signal. It discards the unwanted channels then decodes the chunks for the channel you want to listen to. This means that it:
Proponents of DAB say that it's interference-free and CD-quality, both of which claims are simply false. I've had DAB interference problems while standing still and literally within a line-of-sight of one of the transmitters in London. And the quality is never CD-quality because in practice it's always compressed in a "lossy" fashion, the extent depending on the channel - so at best it's very-good-MP3-quality, and typically worse than that.
One advantage I do credit to DAB is that there's no need to change frequencies from place to place, so you can get a continuous signal even on a long motorway journey without having to re-tune. But then again there's an added disadvantage which is that the DAB decoding process delays the signal by a second or two, so there's no way to get the sound exactly in sync if you have two or more radios turned on in your house.
The move to DAB is technically very similar to the transition from vinyl to CD. However, CD has proved to be a liberating technology thanks to the CD-R, allowing people to distribute music and data on their own initiative and in their own unmediated networks. DAB radio is different because it reduces citizens' ability to be producers, rather than increasing it - we can only be consumers with DAB.
So, for example, as far as I can tell it'll be a lot harder for the pirate radio stations to operate in the DAB space. They'll probably just move to internet MP3 streaming instead, since those can be produced from any home computer with a little bit of free software. (But watch out there too - companies like Apple and Microsoft are trying to replace unrestricted formats like MP3 with DRM [Digital Restrictions Management] formats of their own. Apple has been a key player in elbowing the open Ogg formats out of the picture.)
Radio has a grand tradition of being a liberating technology (much more so than TV), and Trevor Bayliss's wind-up radios were a revolutionary idea because they gave poor people the ability to educate and inform themselves even without access to electricity. The switch-over to digital radio looks set to hobble the medium for very little benefit.