Supporting analog remote antenna units (RAUs) in digital distributed antenna systems (DASs) using analog RAU digital adaptors. In the digital DAS disclosed herein, a head-end equipment (HEE) is configured to exchange digital communications signals with a plurality of digital RAUs. The digital DAS is also configured to distribute digital communications signals to an analog RAU(s), which is not inherently capable of processing the digital communications signals. In this regard, an analog RAU digital adaptor(s) is provided in an analog remote unit to serve as a digital interface for the analog RAU(s). The analog RAU digital adaptor(s) is configured to provide conversions between the digital communications signals and analog RF communications signals. By providing the analog RAU digital adaptor as the digital interface for the analog RAU(s), the digital DAS can be configured to compatibly communicate with the analog RAU(s) and the digital RAU(s).