Yes, my sound card is synched

You can select this mode if you know that your sound card is able to start record and playback at the same time, or with a delay that is constant.

The constant delay can be corrected for in the

 setting explained below.

The system delay will be measured if this is set properly. Check this by performing a measurement of the sound card system delay.

Connect the sound card input to the sound card output, then perform measurements while adjusting the delay. Make sure that the maximum of the sound card impulse response is at 20-60 samples to make sure the left-side tail of the sound card is considered. Below is an example of a response that could be shifted some samples to the left.

By changing the y-axis to dB, it is easier to see the noise floor as shown below.

In this case the sound card delay should be set to about 50 samples to include the pre-ringing before the max is reached.

Note: We have had users that set the sound card delay to 0 samples. When doing this, they do not include the pre-ringing when measuring systems with very short time delay. But in return, the time delay will be correct even without using any correction.