@hsbrock I didn't use that 27 Hz figure; I just used the T/S parameters and a modelling program and estimated the boundary reinforcement from placement in or near a corner.
I don't claim my suggestion is perfect, but it should be "in the ballpark" unless your room is unusually large and/or you have an open floorplan wherein your listening room is open into other rooms. If such is the case, then my assumptions are incorrect.
You mentioned using a corner hence my assumptions about boundary reinforcement, but I probably should have asked about your room.
Duke