Just about all my hi-rez listening is 2 channel. I have both SACD and DVD-A and have titles in both that I listen to frequently as well as rarely. My DVD-A is more rock-heavy, and I haven't been into as much rock these days versus say 20 years ago, so I have about 2x the SACD titles. I recently added a 2ch pre-amp to my setup.
IMO, Mike, you can do better in gauging DVD-A quality than with the RP-91, especially since you're comparing that to the 555ES SACD playback.
That's interesting. I remember reading a lot of good things about the RP-91's DVD-A capability. Though one of the reasons I got it was because it was an open box purchase and therefore cheaper.