Adam, welcome to the Dynaudio family. I've had my 5.4's now for three great years, and the system just gets better around them. I first fell in love with the 3.4's (it didn't hurt that they were connected to 40-50K worth of Musical Fidelity's best), but I thought they were the smoothest, sweetest sounding speakers I had ever heard. I wound up buying a demo pair of the 5.4's for the same price as the 3.4's, so I snapped 'em up, never even listened to 'em til I got 'em home, best purchase for system ever, and they are here to stay.
They do love clean power, and lots of it, so it sounds like you're all set with the Mcintosh amp.
I wish you many years of contented listening, enjoy!
Dan