current FM radio?"
There is some confusion surrounding the term “HD” as it related to HD radio. It is often misunderstood as “High Definition”, like HD television broadcast. The necessity of an additional tuner contributes to this confusion. “HD” as it relates to HD radio really stands for “Hybrid Digital”. There are some sound quality benefits to HD radio, but additional signal resolution (high definition) isn’t one of them. In an HD radio, the digital signal is broadcast as over the FM band from the radio station. Because the signal is digital, it is less susceptible to static, drop outs and interference. That’s definitely a sound quality advantage. The range over which you can pick up the HD signal is about 60% of the range over which you can pick up the traditional FM broadcast. Switching from one broadcast type to the other is done automatically by the HD radio tuner.
An additional benefit of HD radio is that some radio stations multicast. That means they broadcast a second signal, which may be alternate programming. Much of that alternate programming may be more specialized—devoted to a specific genre of music.