Direct by pass refers to bypassing the digital section of a HT pre/pro, it's a feature of the multichannel processer. HT bypass is found on a integrated amp and allows a HT pre/pro to bypass the integrateds pre section, to use it like a 2ch amp when watching movies. Then you can use the integrated amp normally while listening to 2ch sources like cd, without having to disconnect a bunch of wires to watch a movie.