Steve, i cannot agree with Rick`s point, that every nice amp is capable of driving the entry atc models. A week ago we made a demo with my supernait, cd5xs, and Atc scm 20 towers, and 19 entry. Well the result was bad!
I like Atcs, the 20 towers are great speakers, i like the supernait too, and have listened great combos with it! But the match in my opinion, and my dealers, and the other guys that were there ... is a rubbish!
So, a demo i a must! Atc are great speakers, and with the correct amp they sound really good, but if i were you, i wouldn`t buy without a demo!
See i was so keen on the idea of getting some scm 20 classics, but after the demo... not a chance!
Good luck!