I went through the same process as you. I had a 970 and added a Bencmark DAC1 to it vs. modding the 970 or buying the Planet. The sound is beyond belief in presentation, musicality and involvement. My next step was to purchase a used original Planet to use as a transport, until hard times came and I was forced to sell the DAC. Incidentally, the 970 has a very good transport, one of its strengths.
To get the best sound from the 970 set the digital out to RAW (use PCM for movies), the speaker output to L&R (not stereo) and the upsampling to 96 khz (44 is to flat and forward and 192 has too much space with a light bass)and your good to go.
To get the best sound from the 970 set the digital out to RAW (use PCM for movies), the speaker output to L&R (not stereo) and the upsampling to 96 khz (44 is to flat and forward and 192 has too much space with a light bass)and your good to go.