Best wood under audio components?

I am just about finishing my DIY audio rack and wondering about what type of wood would be the best directly under the components? 
I am from Norway and don`t have access to North American maple. Baltic birch plywood is rare also, because we have Norwegian. I would rather have other solid type of wood under my components than plywood, but the efficiency is the major consern, not the outlook.

What type of wood would you recommend?

Thank you! :)