WASAPI

WASAPI is Microsoft’s own ASIO, it talks straight to the soundcard if set to exclusive mode.

As it is exclusive mode, no other application can use the sound card.
No more system sounds at full blast over the stereo!

 

As WASAPI in exclusive mode talks straight to the driver of the audio device, the stream send to this device must match the capabilities of this device in terms of bit depth, sample rate, number of channels and audio format (PCM most of the time) otherwise it is silence.

The program using WASAPI can do this by configuring the audio device to match the source.
In this case we have bit perfect playback.
This allows for automatic sample rate switching as well.

 

The developer can also choose to adept the source to the capabilities of the audio device.
If the source is mono and the audio device 2 channel, the developer might decide to send the same signal to both channels.
If the sample rate of the source is not supported by the hardware e.g. 192 kHz source with a 96 kHz audio device, the program using WASAPI has to do the SRC (Sample Rate Conversion).
Check if the SRC implemented by this program is an improvement compared with the SRC provided by Windows because writing a good SRC is not trivial.

 

Obvious using WASAPI in exclusive mode doesn’t guarantee bit perfect playback.
It is up to the developer of the media player using WASAPI to see to it that the playback is bit perfect.
Bit perfect playback is impossible by design if de properties of the audio file e.g. sample rate are not supported by the hardware.

More...

Audio settings

Crucial is that you match the bit depth.

16 or 24 depending on the capabilities of the DAC.
If you play 16 bits audio (CD) on a 24 DAC using WASAPI, the media player will append 8 zeros to get the required number of bits.
This won't affect sound quality.
In fact, there is a benefit, you can probably use digital volume control without noticeable impact on sound quality.

MC18 Settings

MC18 changed the settings dialog.
WASAPI event style has become the default but if needed you can disable it.

 

 

"Automatic" works in case of my USB DAC.

SPDIF needs "24 bits integer (in a 32 bit package)".

MC15 Settings

Compared with MC14, WASAPI has become more user friendly.

Beside WASAPI there is another option: WASAPI - Event Style
Whatever this Event Style mean, it is most of all developed to cure some problems with USB DAC’s

I use it for both SPDIF and USB

SPDIF

In Output Mode Settings choose the SPDIF out
Check ‘Exclusive’ if you want to have full profit of using WASAPI
(no other sound will play and bypassing the mixer)

 

Nice unreadable pic so double click on it to enlarge.

I don't do any resampling as my DAC supports all common sample rates.

I leave the number of channels to 'Source' as all my audio is 2-channel.

An occasional mono recording will be played over both channels.

Bit depth is 24 as the Benchmark DAC1 is a 24-bit DAC.

USB

In case of USB it is best to use WASAPI – Event Style.
This mode solved a lot of problems with USB DAC’s.
In my case the 50 ms buffer works perfect.
However, WASAPI – USB is pretty sensitive to buffer size.
If you do hit problems try to lower it first.
They say playback has to be stopped when changing buffer size. I have the feeling JRMC should be closed and restarted for options like these to have effect.

 

DSP settings as above

MC 14 settings

In Options > Playback choose WASAPI in the Output mode

SPDIF

These settings work on an iMac running Win7 in combination with a Benchmark DAC 1

In Output Mode Settings choose exclusive mode.

If you don't do this, you are still using the audio engine and therefore the mixer.

In this case (SPDIF out) Present 24-bit data as a 32-bit package should be checked.

This probably got nothing to do with the DAC but with the hardware (iMac) I'm using.

From MC 14.0.144 on, I can leave this option unchecked.

Changed: WASAPI option "Present 24-bit data in a 32-bit package" works more intelligently so less cards should need to change the option.
  (option off by default but will use 32-bit packages if 24-bit packages fail to open; only force 32-bit packages if your hardware is failing to play 24-bit content)

Interact forum

 

 

In the DSP studio, set the bit depth.

The Benchmark is a 24-bit DAC so the bit depth must be 24.

USB

Again check exclusive.

In this case the 24-32 option should be left unchecked.

The Benchmark is a 24-bit DAC so the bit depth must be 24.