So I just got the 4670R Ultra and realized my old receiver can't handle DD+, and the Roku won't transcode to DD. Very disappointed since I expect 5.1 for everything. However, does anyone know what format/codec is used to downmix the 5.1 tracks to stereo? I'm currently using Dolby PLII (cinema) to bring some semblance of 5.1 back, but dialog especially does not sound nearly as clear. I have DTS presets available as well. Thanks!