This might look a bit wild. Connector is not an RCA but a Redel as I like these better on my personal gear. Voltage divider is differential 5k 5R 5k. The center 5R is chosen to emulate a 5R coil which is a typical value for the MC cartridges I use. This is then connected to 2 BNC cables for balanced connection to the QA403.
Also check this thread: Phono preamp measurement setup