They are using the latest versions released probably?
Access Virus B v4.9
Access Virus C/KC/Indigo v6.6. However. According to the official Access Virus website the latest version available for download is 6.5 (under Downloads/Discontinued products/Operating systems) - but the Synthesizer ROM Archive website says it's v6.6. I checked the .bin file and for sure it says 6.6. This is a bit weird.
Anyone knows why there is no 6.6 update available from Access website?