I haven't used a 970 or 1070, but my understanding is that their behavior is as follows: you can select Pro Logic IIx by pressing the Dolby button on the remote to cycle through Dolby processing modes. Once you've used PLIIx on a specific input with a DD (or DTS) soundtrack, it will remember that preference the next time you play such a soundtrack on that input. There are three mode buttons (Dolby, DTS, and Stereo) that each offer a range of options depending on the source (DTS will do nothing with a DD 5.1 track but will offer NEO:6 with a stereo input; Dolby will offer PLIIx with a DTS input; ...). You don't have to press "Dolby" to cycle through Dolby modes each time you start a disc because it will remember the mode you used last for that particular input format on that source - you'll have to set it the first time you use each different format on that source.