WHRB is a very tough grab anywhere near Providence. It's got good height but the ERP is only 1700 watts, and they've got a directional antenna pattern that nulls somewhat to the NE and SW (in part to protect WBRU). WBRU, OTOH, blasts out over 18,000 watts from (almost) downtown Providence.
I don't think WBRU broadcasts in HD Radio, but if they do, kiss any reception of WHRB...no matter how good your radio...goodbye in the metro Providence area. The IBOC sidebands just put out too much noise and the WHRB signal is too weak to get reliable reception.