Single channel shown:
Both primary (IN) and secondary (OUT) windings of the Consolidated Audio step-up transformer are floating i.e. neither end is internally connected to ground. This allows for symmetrial as well as asymmetrical connection on the input and output side of the transformer.
Asymmetrical connection (RCA / Cinch shielded interconnect)
Depending on the internal wiring of turntable / tonearm/ headshell the shield of the interconnect between MC cartridge and SUT may miss a proper ground (GND) connection (see ? on left side of Fig. 2). This may be the cause of interference (hum) problems origiating from the SUT's input side. A simple solution to eliminate this hum is to add an external (shield to the SUT GND terminal (see ! and dashed line in Fig.2).
Using the asymmetrical MM phono input (RCA socket) provides a ground connection for the interconnect shield (see on the right of Fig.2). Any hum problems originating from the SUT's output side are thus not to be expected.
An appropriately configured interconnect cable may provide a symmetrical connection from MC cartridge to step-up transformer. The shield of the pair of input wires may be connected to ground either on the turntable side (A) or on the SUT side (B) as shown in Fig.3. Don't connect both A and B to GND at the same time to avoid a ground loop.
Assuming a MM phono stage with symmetrical XLR input a properly configued RCA to XLR interconnect may be used. The shield of the output pair will be grounded through the XLR phono input socket.