No, the PRO1/2/2C all have their own inbuilt DSP pcb which is unique to each console. The DL371 engine was designed to be the remote DSP engine (or brain) to the PRO3, PRO6, PRO9 series of consoles only, so for this reason connecting just the DL371 to a PRO1 (for example) would not achieve anything.

However in other circumstances, any of these above consoles can be connected together in a process called tie-lines; this is a process of sharing audio from one IO box between two different Midas consoles such as a PRO9 and a PRO2 and is highlighted in this informative video link: