Steve - The DVMega AMBE3000 initially came out as a 'shield' that would sit on an Arduino, with an additional audio board so you could plug in a mic / speaker and hold a QSO over a D-Star(?) network via a PC without any local RF.

The next evolution was the 'carrier board' which  removed the requirement for the Arduino , and meant you could plug it directly into a PC and use the PC sound card rather than the additional audio board + Arduino.

Peter - does it look like the carrier board is doing anything other than converting USB to serial?  If not, then hopefully Analog_Bridge can interface with it directly. If there is an additional microcontroller it might be best going straight into the AMBE3000 with a serial adapter

Cheers all for taking an interest in this, much appreciated.