Again, for movies, I doubt too many people could hear much difference between the 3808 plus the Anthem, or the Rotel. On the other hand, your room is not small, assuming you have >=8 ft ceiling. So if your want to make sure you have enough power, go for the P2. I just don't think the Rotel will get you much more power (60% or so) than the Denon.
I know people argue that the fluctuation in impedance of a speaker is one of the reasons why a more powerful amp will improve SQ with more power. I would say in most cases that's not true. Speakers such as the Paradigm Studio series may have "holes", but that's usually still at 4 ohms or higher. Besides, such 'holes' typically don't exist in the current hungry low frequency range. If you spend enough time searching the web you will find some impedance versus frequency curves of many popular speakers. With all due respect, there are people who experienced those no brainer, day and night types of SQ improvement after adding an external amp to mid level recievers such as the Denon 38XX or Yamaha RX-V2X00, but there are also many people reported marginal or not noticeable differences. You really have to experience it yourself.
I suggested the Anthem mainly because it will give you much more power for the front channels, the increase in power is significant enough that you won't be able to blame your power amp if you still don't think your Digms are performing at their full potential. If you main interests are movies and/or multichannel music, then the Rotel may be marginally better, but then what a waste to let the 3808's decent amp section unused!
