Comment 7 for bug 732977

According to http://portaudio.com/trac/ticket/76 PortAudio (the library we use to interface with sound hardware) only supports one ASIO device at a time. Like I said, really not sure why you're able to open 2, might be a PortAudio bug (or maybe they've made progress on that ticket and the fix just isn't totally working yet, who knows).

I know WASAPI has both an exclusive and shared (mixed) mode. I'd imagine the shared mode is higher latency than the exclusive mode (which is practically equivalent to ASIO) and I don't know how to distinguish between the two modes in software, but I've always gotten very low latency with WASAPI in Mixxx and I know Sean (one of our Windows guys) recommends WASAPI.