Three ways to aggregate audio on windows, ASIO4ALL, ASIO PRO LINK, VB Audio Matrix - Смотреть видео или скачать видео в MP4, музыку MP3 на телефон или компьютер
Only one way seems to work. Maybe you can get the other two ways to work, but I couldn't.
This video shows you how to use two video interfaces at the same time, so you can use two 2 input audio devices together to get 4 inputs into something like ableton.