Definitely a radio like the Superadio with high sensitivity will help since the metal in the building's structure is going to attenuate the signal. Experiment with the placement of the radio in the room. Perhaps try attaching a length of small #18-24 gauge wire around 10' long (about a full wavelength on FM) to the whip antenna and try to get the wire near one of the skylights if your warehouse has them. You could make the wire longer if there is a way to safely get the wire up higher, preferably near a skylight, or in the absence of a skylight, make sure the radio/antenna is along the wall that's facing the stations you want to hear. The additional wire will increase the signal voltage to the radio, bringing in previously barely audible stations to a listenable sound level. I know, it works based on my experience with several portable and clock radios with low sensitivity.