Directsound vs WASAPI vs ASIO Options

[Midiman]

After reading many of the posts on this forum, it appears that there is no evidence that ASIO or WASAPI sounds any better than Directsound on Windows 7. I understand the importance of ABX testing - and I am interested in a way to do a double blind test of such claims. Let me first of all state that I cannot hear any difference. For me to be objective, I have used the same player for all tests - foobar2000 - and simply changed the Output from Directsound to WASAPI to ASIO. However, to do this, I have to stop the playback, change the driver, and then restart playback. This means comparions are doubtful at best due to the delay involved and my knowledge of what driver I selected.

How have others conducted such tests? Please note I am not trying to prove a difference exists - just to find a way to do the test properly. The ABX plugin for foobar2000 has been very useful to compare different WAV files. Obviously, one cannot use it for this sort of experiment.

Thank you for any suggestions or pointers to where this has been proved one way or another.

[Roseval]

The difference between ASIO/WASAPI and DS is that DS always use the Win mixer.
All audio is dithered by the mixer.
If the sample rate of the audio differs from the one set in the sound panel, it will be resampled.

ASIO/WASAPI (exclusive) will bypass the mixer.
No dither and no resampling if the hardware is able to play the sample rate of the audio.
This is about the protocol. The media player might do all kind of DSP like volume control + dither.