Taken from Analog Rytm manual:

Main Out L/R. Use either 1/4” mono phone plug (unbalanced connection) or 1/4” (Tip/Ring/Sleeve) phone plug (balanced connection).

When using 1/4 TS or TRS cables with Apogee sound cards you must select “Instrument” in Maestro.

Taken from Apogee manual:

When using the 1/4” input, the source must be set to “Inst”.