Interesting finding... Wasapi to outboard DAC pointless?

[DLA123]

I just did a few listening tests with a few different configurations, all using the same 16bit FLAC Bob Marley studio recorded track. The results were interesting, but the most surprising finding was that I was unable to tell any difference in sound quality by using WASAPI output to the DAC versus just using the laptop's onboard sound driver output the DAC. Here are the different configurations I tested:

 

1) Foobar2000> Wasapi> Realtek HD Audio Driver> Laptop Headphone jack.

2) Foobar2000> DS> Realtek HD Audio Driver> Laptop Headphone Jack.

3) Foobar2000> Wasapi> USB Asynchronous DAC> DAC headphone jack.

4) Foobar2000> DS> USB Ascynchronous DAC> DAC headphone jack.

 

Findings:

 

- As expected, much better sound going through WASAPI to the laptop headphone jack(#1), than simply using the onboard audio driver to the laptop headphone jack (#2). WASAPI really does make a huge difference,

 

- Suprisingly, I was unable to hear any difference in sound quality between using WASAPI output to the DAC (#3), and just using the direct sound to the DAC (#4).

 

I am using a MusicHall 25.3 USB Asnynchronous DAC which has a notoriously good headphone jack, so this naturally came as a surprise to me that I could not hear any difference in sound quality when using the WASAPI output to this DAC.

 

Any idea why or what is going on here? Thoughts?