Both ASIO and WASAPI work perfectly for me via Foobar. I have WASAPI with exclusive mode enabled; unfortunately, I don't think ASIO has exclusive access. My system sounds manage to come through during playback. I use WASAPI most of the time, until I want to playback DSD, where I enable RUSB ASIO path via the SACD decoder ASIO proxy. BTW, all Foobar visualizations should go completely cold DSD playback happens correctly.
For people that want to play DSD with the Invicta/Mirus/HD/HP/Herus:
The only units that don't work on WASAPI over Foobar for me are C-Media CM6631A-based DAC units, not sure why. They playback 16/44.1, but don't play anything higher. ASIO works for all sample rates and bit-depths, though. (Anyway, off-topic, but just an interesting note)