Generally, unless you have very specific reasons to use WASAPI, like for example bit-perfect output to an external receiver, it is recommended to stick to DirectSound, since it is the most tested and well behaved of the output methods. So far nobody has been able to provide definitive proof that WASAPI output (or ASIO output for that matter) offers any benefit over DirectSound output. What I mean to say is that alternative output methods lead to lots of problems without any perceptible benefits. The same is true for bit depths which exceed 16 bit resolution, and sample rates beyond 44.1 kHz.Instead of buying into the audiophile arms race of dials which go up to eleven and sample rates which touch the MHz range, it is much easier and less of a hassle to just stick to the proved realities, and that is that CD quality audio (16bit/44.1kHz) is good enough, as is DirectSound output.
Well, I must disagree with this statement. As a semi-professional recording engineer I can vouch that there is a perceptible difference between 16 bit and 24 bit recordings.
I only record classical music and there is more "life/reality" - call it what you will - in a 24 bit recording made in a good concert hall.
As I am now over 60, I personally cannot detect any difference between 48 KHz and 96 KHz.
Having said that, it is most pleasant that record companies like Chandos and Hyperion and BIS are now providing 24 bit masters for download.
As for 32 bit, I suspect that is simply overkill and is why the pro audio guys will tend to ignore it.
Obviously, you need decent kit to hear the difference.
My monitor speakers can be fed from my Realtek onboard sound card or digitally via my EDIROL UA-101. There is little, if any, difference - the speakers are cheap! However, if I use my ATH M-50 headphones, the headphone amp in the UA-101 is noticeably better than the headphone amp in the monitor speakers.
Similarly, the ASIO driver is markedly "cleaner" - whatever that means - than the WDM/Direct Sound driver - again, on headphones in the UA-101.