Last spring, Amazon launched its long-rumored live audio-streaming platform, Amp. The pitch was to reinvent radio with “an infinite dial of shows.” Amp offers users access to a vast, built-in music library to create their own DJ sets with. No need to buy songs or flirt with the DMCA; just make a playlist, go live, talk in between tracks, follow the chat and even invite callers. When I wrote about it a year ago, it showed promise, but it was iOS-only, light on users and had a limited feature set.