The RTi12 may look imposing, but they don't present a difficult load to the amplifier. They are 8 ohm nominal with 90db sensitivity. Any decent receiver should be able to drive them just fine.
The Denon 987 is the equivalent of the Denon 2807 and is a good solid mid-line receiver. To be honest, I don't think you would hear a difference between the Denon or Denon/Emotiva unless you listen at reference levels, i.e. very loud. If you biamp the Denon, you are actually putting almost as much power into the speaker as with the Emotiva anyway.
If it's a tweak you need to try just to see for yourself, at least the Emotiva is affordable and returnable.