JACK is a professional sound server daemon that provides real-time low latency connections for both audio and MIDI data between applications that implement its API. The API can be used through either JACK1 or JACK2.
JACK Audio Connection Kit vs Soundflower opinions
jack is much too complicated. soundflower was so simple, just so buggy. how has nobody made a good copy of it yet...
JACK Audio is much more complicated and requires actually starting up the server for routing to take effect but it fundamentally addresses the same issue of routing which Soundflower does.
jack audio doesn't seem to stream screen sharing audio
Voicemeeter is Audio Mixer Application endowed with Virtual Audio Device used as Virtual I/O to mix and manage any audio sources from or to any audio devices or applications.
VB-Audio CABLE is a Windows Audio Driver working as a Virtual Audio Cable. After installing the VB-CABLE driver, a new playback device appears in the audio device list and can be set as default device. VB-CABLE can be set as the default device, just like any regular audio device.
VB-Audio Virtual Cable vs Soundflower opinions
BlackHole is a modern macOS virtual audio driver that allows applications to pass audio to other applications with zero additional latency.
BlackHole Audio Loopback Driver vs Soundflower opinions
It is basically the same thing as Soundflower, but it works for Catalina. Nothing new to learn.
Blackhole takes off where Soundflower left off and supports modern macOS. Development is live and active.
Synchronous Audio Router is a software-based audio routing driver for Windows. You can create any number of Windows audio endpoints, either playback or recording, and route them using any digital audio workstation software which supports ASIO, all with low latency.Discontinued
The last version (0.13.1) was released in April 2018. Many issues in the repository going unanswered.