TumTaster adds download links to audio posts and gives you a playlist of all the tracks that you've seen for easy access.
TumTaster uses SoundManager2 V2.97a.20140901 for managing MP3 playback and FontAwesome v4.2.0 for icons.
TumTaster for Google Chrome can be installed here - https://chrome.google.com/webstore/detail/nanfbkacbckngfcklahdgfagjlghfbgm
This extension is open source and all source code can be found at https://github.com/bjornstar/TumTaster.
If you'd like to show your appreciation for this extension, you can do so at paypal.me/bjornstar
Disclaimer: TumTaster is neither affiliated with nor supported by Tumblr in any way.