[DuplicateCat]

I'm shocked when I receive a vintage hd 480i and listen to symphonies and electronic dance music. It gives me a feeling that this little headphones can handle all the music types. Unluckily, it is difficult to search the history of hd 4xx series, like hd 4x1, 4x0, 4x5, 4x4, etc.
So are there any recommended websites or materials which tells the detailed development of hd 4xx series? （e.g. hd 414 → hd 424）
Thanks a lot!