Re: Wavelength in kHz?
75Khz is the deviation of FM signals from their nominal carrier frequency when fully modulated.
Lord knows why Halfords decided to put that into their spiel..... It has no relevance whatsoever, unless you are comparing the audio quality of broadcast FM with 2-way radio type FM, which has a deviation of around 5Khz.
As everyone knows, the frequency of FM broadcast is 88-108 in most of the world, and Am broadcast around 530-1600Khz, except for the aforementioned 1500 metres in old money.
DAB of course could be broadcast on pretty much any frequency - it's just that the Band 3 frequencies around 200Mhz are fairly well suited to this, plus, in the UK, there were pretty much available for use from the late 80's onwards.
Audio quality better than AM or FM? Er, has the capability to be so, but in practice is not implemented. Arguably good AM sounds much better than 64kb/s MP2.