Apparently model 40n is on the warmer side, class AB.To serve for different customers I believe. For instance the 7000n and 40n being an all in one system is aimed at general consumes, hence they have a warm and smooth sound. The 8006 and model 30 on the other hand is aimed at audiophiles going for separates hence a more neutral and detailed sound.
30n was more on the neutral, class D design.