You can use Pro Logic IIx in conjunction with DTS 5.1 sources with the 1070 in order to have the sixth speaker active. You can also use NEO:6 (what was once called DTS ES Matrix).

You can also use "6 Stereo" in a 6.1 setup, assuming that the source is analog or PCM digital. The 5/6/7 Stereo mode can't be used in conjunction with Dolby Digital or DTS sources.