The sound quality via DAB is every bit as exceptional as from resident digital content. In fact, you'd be hard pushed to tell whether you were listening to DAB or a resident track, encoded at a decent bit rate. Listening to a variety of stations, playing everything from rock to jazz to classical music, the B20 turned in a flawless performance. If there's one caveat, it's that you really need to use the telescopic aerial for good DAB reception - there is an option to use your headphones as an aerial, but the reception suffers significantly as a result.
Like the Cowon D2, the iRiver B20 also receives DMB (Digital Media Broadcasts), which gives you the option of actually watching TV on the device. Unfortunately, there is no DMB service in the UK, so this is something of a wasted feature for us Brits. DMB is widespread in Korea, which is why Korean companies like iRiver offer support for it. That said, DMB broadcasts started in Germany last year in conjunction with the World Cup, while a trial is also currently running in Paris, so hopefully we'll see UK broadcasters dip their toes in the DMB waters soon.
You can also record DAB broadcasts to the B20, although the modest 2GB capacity of my review sample wouldn't leave you much space to do so if you've already got a lot of music on the device. It's therefore a good thing that the B20 has a miniSD card slot, so you can augment your storage easily and cheaply. With a 2GB miniSD card costing around £12, you could double the capacity of the B20 without breaking the bank.
The B20 also supports the DAB EPG feature, allowing you to schedule recordings using programme data supplied by the broadcasters. However, even though I often found the EPG symbol flashing while I was listening to certain stations, I wasn't able to access any EPG data. To be fair, most of the stations in the UK are only trialling their EPG functionality now, so it could well be that part of the equation at fault rather than the B20.
However, it's worth remembering that the Creative Zen uses standard SD cards and supports SDHC, which means capacities of up to 8GB are available, with 16 and 32GB on the horizon . The Cowon D2 also uses standard SD cards, but doesn't support SDHC, although there are rumours that a firmware upgrade will address this issue. Either way, standard SD is definitely a better option than miniSD, which is even less prevalent than microSD.