is there a good guide to bitrates/sound quality to UK radio.Satellite >= DVT > DAB, but where is FM?
With FM the main thing affecting quality is simply how good of a signal you pick up - is the signal strong enough, is there any interference, etc. Hissing and dropouts are symptoms of poor reception.
With digital broadcasts, you can't pick up a "fuzzy" signal, you either get the bits successfully or you don't. So, once you've picked up a digital broadcast, the quality's going to be determined by the digital parameters like which codec and bit rate is being used. Unfortunately I've got no idea what they use for the digital broadcasts.