SPDIF
This is the digital out of the soundcard.
More about SPDIF
Speaker setup
Configure is disabled here as the audio is send straight to the DAC.
Not to be mistaken for unaltered.
Properties
General
Not much to configure here.
The Properties button gives information about the driver.
I use the standard Windows HD drivers.
Formats
Check the sample rates supported by your DAC.
If you play audio with a sample rate not supported by your DAC, the Windows audio engine will do the sample rate conversion.
If you have an upsampling DAC you can use this settings to compare the SRC by Windows and your DAC. Assuming Redbook audio (44.1,) uncheck all but 44.1 and the DAC will do the upsampling.
Uncheck all but the highest input of the DAC and Windows will do the upsampling.
Level
In general it is recommended to set both volume and balance to 100 to avoid any impact of the digital volume control.
Enhancements
I belong to those silly purist who think the greatest enhancement is to disable them all.
Advanced
By default Win runs in shared mode.
This allows for mixing e.g. you watch a video but like to hear a notification when an email comes in.
Mixing can only be done when both audio streams have the same bit-depth and sample rate.
Hence all audio streams are mixed and if needed resampled, to the settings in this panel.
Mixing means converting to float, mix, dither, convert back to integer.
Set the bit depth to the max supported by your DAC.
Today almost all DAC support 24 or even 32 bit.
24 bit dither is at -144 dBFS, you simply won't hear this as it is way below the noise floor of your gear.
Adding 8 bits to a 16 bit recording won't affect sound quality of course.
Set the sample rate to what is common.
This is 44.1 kHz most of the time.
Using this setting is probably undistinguishable from "exclusive" as long as you play CD quality.
Allow applications to take exclusive control should be checked if you plan to use WASAPI in exclusive mode.
Give exclusive mode applications priority might save you a couple of dropouts.