Long-time Rogue Amoeba users may recall that the very first version of SoundSource shipped way back in 2003, as a handy tool for switching audio devices. You might also remember that we had an application called LineIn, which enabled audio play-thru from input devices. LineIn last saw a major update in 2005, while SoundSource was originally retired back in 2012.
The functionality of both SoundSource and LineIn has now been wrapped up in SoundSource 3. We've modernized everything into a single new application. Full control of your audio devices has now returned to the menu bar, and LineIn's audio play-thru functionality has been incorporated, with greatly reduced latency now possible with internal improvements in our audio code.
The new SoundSource 3 should prove useful for MacOS users for many years to come. For the history buffs out there, more information on our old SoundSource and LineIn applications can be found on this page.