We suggest that to get a good output level the gain on the VoiceMaster Pro should be set so that the signal peaks at -6 to -4dB on the output meter. The VMPro meters are calibrated in dBFS, where 0dBFS is the maximum input level to the optional A/D converter - equal to +22dBu - above which clipping occurs. The input to your sound card may have a lower maximum input level to which the VoiceMaster Pro meter is not calibrated. If you are connecting via an analogue to it and are seeing a good level on the VoiceMaster Pro output meter then it may cause the sound card input to clip the signal. In this case, you simply need to back off the output fader to compensate.
As an example, your sound card may have a maximum input level of +14dBu - 8dBu lower than the VoiceMaster Pro. In this case, you should reduce the output fader setting by about 8dB so the signal is peaking at somewhere between -14 and -12dB. You can find out the maximum input level for your sound card in its manual. As long as you ensure the input level LED meter is peaking at -6 to -4dB then you should adjust the output fader so that the signal is peaking at about 6dBu below the maximum input level of the receiving device.