Those Def Tech speakers are fairly efficient so most any AVR will be able to easily drive them to loud volume levels. For Denon models, review posts #1 and #2 in the Owner's thread linked below to get an idea of what features are available at each price point. Note also that depending on your time frame the new 2014 models of all brands will start being released in the next several months so you can either wait to get a good clearance deal on a 2013 model or get the newer features on the 2014 models.
Normally, there is not a lot of difference in power between comparably priced units. And not usually a very dramatic difference between most receivers generally. If you are worried about having enough power, you should look for a receiver with preamp outputs, so that you can add an external power amplifier, which can be as powerful as your budget allows. Most likely, though, unless you listen at literally deafening sound levels, you don't need any more power than a normal receiver.
As for receivers in different price ranges, you tend to get more and more features as you move up the line. Which features are useful will depend on what gear you want to connect to it, and what you want to accomplish. For example, some of the expensive receivers, like this one (which is discounted because it is last year's model, and is what I would buy if I were buying something at its price point of $1500):
have great video processing. But that may not matter to you, if all you are going to do is watch BDs. And it may not matter if your TV has great video processing (I have no idea about your particular model). The receiver also has many other features that could be nice to have, but most of which are probably not going to be necessary for you, though it really depends on what you want to do.
Here is another receiver I would consider (and is what I would currently buy at its price point of $700):
It is also from last year, which is why it is discounted. It is likely that it, too, has more features than you need. But, again, it depends on what you need it to do.
If you want advice on features, you might want to tell us everything that you plan on hooking up to it. But judging from your statements about not needing fancy features, most likely, you will be happy with a $500 unit instead of one of the more expensive ones above.
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