It's interestingand insightfulthat you would think underpowering your speakers might cause a blowout. Most people would think that overpowering a speaker might cause damageand it canbut so can underpowering if you like to play it loud. If you limit the volume so it always sounds clean, you shouldn't have a problem, but if you drive the amp near its limit, it could go into clipping, and the resulting distortion can cause the speakerespecially the tweeterto overheat and fail.
Another potential issue arises from mating low-impedance speakers to an amp that is not designed for them, but I don't think this is the problem in your case. Let's take a look at the specsthe Energy CF-50 is specified with a nominal impedance of 8 ohms and a minimum impedance of 4 ohms, while both Definitive models are spec'd to be "8-ohm compatible," which I assume means they have a nominal impedance of 8 ohms; I don't know their minimum impedance. The CF-50 and C/L/R 2002 can handle power from 20 to 250W, while the SM 350 can handle 20 to 200W.
The Denon AVR-1912 is spec'd to output 90 watts per channel into 8 ohms with "low-impedance drive capability." However, the manual says the speakers must have an impedance from 6 to 16 ohms, which I assume refers to the nominal impedance, and 6 ohms isn't all that low. Still, taking all these numbers into account, I think the Denon should have no trouble with the impedance of your speakers.
On the other hand, 90 watts is kinda wimpy for these speakers, which would probably be happier with 200 watts than with 90, especially if you like to crank the volume. So yes, I think a more powerful AVR is warranted in your case. You don't say if you have a powered subwoofer, but that can also reduce the workload of the AVR if you redirect the low frequencies in the main channels to the sub.
I'm also concerned that you are mixing Energy and Definitive speakers in the same system. I always strongly recommend that all speakers in a surround system come from the same manufacturer to maintain a consistent tonal balance. Unless you really like the sound of your current system, I'd return or sell the Energys and get two more C/L/R 2002s for the front left and right, which would give you three identical speakers across the front. Alternatively, a pair of Definitive towers would also work very well with the rest of your speakers.
If you have an A/V question, please send it to firstname.lastname@example.org.