The optional card contains a high spec, low jitter A/D converter and gives the VoiceMaster Pro a 24 bit S/PDIF digital output capable of up to 96KHz sample rate on an RCA phono connector. It has a word clock in connector for syncing to external devices too. Unless your computer has a S/PDIF input built in (some cheaper internal sound cards do) it does not allow you to connect the unit directly to your computer for recording into your DAW - you will need an audio interface/sound card with a RCA S/PDIF input for this (check out the Focusrite Saffire as an example).

There are a few reasons why you may want a digital output from the VMPro:

- cable interference is not an issue with digital signals so no noise will be induced as with an analogue connection, thus the recorded signal will have a slightly lower noise floor.
- the VoiceMaster Pro converter is of better quality than that in your audio interface/sound card.
- all analogue inputs on your interface are being used so you only have the option of connecting to it via S/PDIF.

The part is 'MH444 Platinum ADC R2' (some stores may refer to it as just Voicemaster Pro digital card or something similar). For price info and to find out where you can purchase one please contact the distributor for your country (contact details can be found in the distributor section).