I recently learned that 104.1 WBMX is transmitting 4 HD channels, but my Sangean HDT-1X only receives the WBMX analog signal with RDS. I receive solid signals from all the other FM HD radio stations in the area, including those that transmit 3 HD channels such as 89.7 WGBH-FM HD1/2/3, 98.5 WBZ-FM HD1/2/3, 100.7 WZLX HD1/2/3, and 103.3 WODS HD1/2/3. Now I've learned that the HD transmission spec was revised to accommodate 4 digital channels which might be confusing my older receiver. As far as I can tell, a receiver software upgrade isn't available. I find it hard to believe that the FM HD transmission spec was revised without being backward compatible. Do I need to buy a new receiver to receive WBMX HD4 and other radio stations transmitting an HD4 channel, or is there something in the electronics of the HDT-1X that prevents reception of the additional digital bandwidth?