If it's anything like my Marantz SA-15S2b SACD player, it's not at all warm, dark and flat. Mine has two filter settings that definitely change the sound characteristics and the 30N may have more settings to fiddle with.
A lot of that warmth that people hear with Marantz is misunderstood, as I've found out. Using Isoacoustic Orea footers cancelled a lot of vibrations, focusing the soundstage and eliminating smearing, which many attribute to warmth. It also allowed the music to emanate in all directions instead of laterally.
Switching the filter settings that I mentioned changed things to give me a more detailed, airy and expansive presentation. The Marantz sound does err on the warm side of neutral, but not as much as some people think.
All the best,
Nonoise