If Reason had to support inputs from primarily half-duplex, polled audio APIs such as DirectX, MME and WASAPI, it would basically have to contain an implementation of ASIO4ALL.
If Audacity can record and play back at the same time with acceptable latency, then it contains something like that.
I recommend you to use ASIO4ALL for this purpose, if you are still deciding which ASIO-capable audio interface to use.
When ASIO4ALL is used on a single audio interface driver, that is designed to run in full duplex, with the same clock for inputs and outputs, it merely does a cumbersome conversion from a such half-duplex APIs to ASIO.
(ASIO is on the contrary, a natively full-duplex, callback API)
ASIO4ALL can also combine streams that have different clocks, but that will always be destructive, and probably unstable.