We sell and recommend the VXpocket 440 card for portable 4-channel measurements where you need all channels to be synchronized (find correct delay times).
To set WinMLS to measure 4 channels, go to Measurement->Settings… and select 4 ch. as shown below
For the VXpocket 440 to be synchronized (the delay is the same for all input channels), the WinMLS mixer must be set to control the Windows mixer. Go to Measurement->Sound Card… and select the settings shown below
Click 
and
select the settings shown below.
For a greater than 2-channel measurements, WinMLS
does not control the input or output levels. Therefore you must set the levels
using the Digigram mixer shown below. Open the mixer from the blue Digigram icon
on the task bar 
.
Set the Analog In sliders to set the level for channels 1 and 2. To set the level for channels 3 and 4, you need to select the VXpocket 440 Mixer #2 from the menu as shown below.
If WinMLS is unstable, this is probably because the input level is set to the minimum. Make sure the levels are set above the minimum value for all input channels that are to be used.
After you are done go to Options->Save current configuration as default to save the Digigram mixer settings so they are the same the next time you turn on you computer.
The VXpocket 440 has three input gains: 0dB, +30 dB, and +48 dB.
0 dB is the line gain, +30 dB and + 48 dB are the microphone gains.
For a gain of 0 dB, a +10 dBu maximum input signal gives 0 dBfs (digital full scale).
For a gain of +30 dB, a - 20 dBu maximum signal gives 0dBfs (digital full scale).
For a gain of +48 dB, a - 38 dBu maximum signal gives 0dBfs (digital full scale).
Let N be the nominal input level, and H the input headroom.
The following must be done to switch the input to microphone gain:
• N + H = -38, e. g. Nominal = -44 dBu and Headroom = 6 dB,
• if the fader Analog In is set to a gain higher or equal to 0 dB, the microphone gain is +48 dB.
• if the fader Analog In is set to a gain lower than 0 dB, the microphone gain is +30 dB.
• the Analog In balance fader should not be used in microphone gain mode, as this would modify the microphone gain value.
