Having recently attempted (and failed) to us two audio interfaces via the ASIO4ALL driver, I'd like to suggest that S1 be able to simultainiously handle multiple audio interfaces natively.
Often hardware (such as the ********* UMC404HD)) have superior drivers. Using a comparative kludge like ASIO4ALL givers substandard results, and in my case, proved to be unstable (it made S1 loop in transport).
This is a next-evolution request, but multiple native input support is important.