Okay, so it turned out to be the sound modes. When streaming the aforementioned MP3 via Airplay, the MOVIE, MUSIC, and GAME modes all result in the AVR display saying STEREO and the crossover settings working as configured. But if I press PURE, the display says DIRECT and the mains receive full strength signal with no attenuation all the way down to 5hz. This is the case regardless of the crossover setting, speaker size setting, or Subwoofer Mode setting (LFE / LFE + Main).
This seems wrong to me, like maybe a firmware issue. Can anyone explain to my why it should work this way?
Living Room: Denon 2113ci + BIC V1020 + Panasonic BDT220 + AppleTV + uVerse DVR + Panasonic P42S2 plasma
Theater: Denon 2313ci + Klipsch RW12d + Panasonic BDT220 + Mac mini + uVerse wired receiver + Epson 8350 PJ + 100" screen