As Karls touched on, you need current to drive these low sensitivity speakers well. In addition , their 4 ohm impedance means you need an amp that will be stable at low impedance and high current. That usually means SS unless you go big on the tube amp. I have the Contour 2 MkIIs and drive them with Pass Aleph 2 monos (They are single ended SS Class A amps). These amps double as my room heaters in the winter (no joke) and their high current is needed to overcome their single ended amplification technique (what also makes them sound so good) to get the dynamics and transients right for the Dynaudios. If you really like the tube sound and cant' go really expensive for a huge tube amp, try a Threshold T-100 or 200. Both can be found used for 1300-2000 if you look around some. I can't say anything less than amazing for the T-200. Very dynamic and doesn't sound solid state. If you have the means, consider the Alephs monos. You won't be disappointed. There are several great large tube amps, but you may notice a little lag on the low end dynamics (an admitted weakness at least in my Dynaudios) that is compunded by the valvular nature of tube amplification. Hope this was helpful. I think you've chosen a great speaker. It takes a little more to drive it well, but it's well worth it. Happy listening,
Todd
Todd