The Denon should have no trouble running those ELACs... especially just 2 channels, they claim 4-ohms, that dip to 3.4...
but Home-theater-review had some different numbers. Regardless, most mass market gear at this level should work together pretty easily. If there was a problem in the amp stage, it would likely trigger the safeties rather than cut the output.
In general I agree with Leemix's advice:
LPF for LFE should be 120.
I would try your XO at 80... I'm an octave-above kinda guy, myself, but 100 might be good too as the FR is a pretty steep drop starting at 60Hz.
Along with experimenting again with Audyssey:
Reset all levels, distances, eq changes... anything... just to eliminate potential mix up.
Audyssey should nail your distance fairly accurately for the towers, and then your sub should measure about twice as far depending on its on-board DSP. (These are arguably the best things that Aud does, IMO.)
Beyond:
Did you reset your receiver to the 4-ohm setting? If yes, change it back to 8.
Keep in mind that your speakers
ARE low on the sensitivity scale. Your receiver should still be able to hit reference level if you choose, but you are going to be pushing it pretty much all the way.
For me, I listen to most music at -15 to -10dB. Sometimes I push it a little higher. The idea of not going past "50%" isn't really a thing but for wives that don't understand.
More info would be nice, though... did this all only happen after you did Audyssey?