That's the problem with dyns, they are quite difficult to drive. You have to be prepared to have a very good high powered amp, if not, just forget about them and get something else. No doubt, they are very good speakers but if not properly driven, you are not giving them justice.
I remembered my friend had the Dyns special twenty five bookshelf being driven by a passlabs x-100. It didn't work as the amp was struggling (that is a passlabs and still we were scratching our head, why). He sold it after trying all the tweaks he could think of in his system. He replaced it with a sonus faber electa amator 2 .