https://ddmf.eu/virtual-audio-stream



How it works:

Usually, all programs send their audio output to your soundcard independently. With Virtual Audio Stream you can route the output signal of any application to be the input signal of any other application. Furthermore, using the effect rack, you can route all audio through a set of audio effects.

A virtual audio driver transmitting sound from and to applications in CD quality
Four virtual audio cables for ultimate routing flexibility
A VST effect rack which can treat sound from up to four sound cards independently!
Instant access to the myriads of VST effects, many of them free!
High-class equalizer, compressor and limiter by DDMF optionally included

What you get are actually two products in one: a 4x2 channel, CD-quality virtual audio driver that takes care of routing all your audio signals to and from any application, and an effect rack application that can wire up chains of VST effect plugins (the de-facto standard format for Windows audio effects) for up to four soundcards independently!