@tomic601 is correct. They are not hard to drive at all for great sound.
Comments like these are simply not correct:
That amp will not cope well with very hard to drive Vandersteen speakers. I would echo Soix's POV exactly. Those speakers need a bit more oomph.
I drove my pair of Vanderteen model Sevens with an Art Audio 28wpc stereo amp that was simply amazing sounding. We use our own 40wpc class A tube amps that make them really sing also.
Zero feedback amps make Vandersteen speakers really sound their best also.
Happy Listening.