Overhead of using big singleton with all files includes

I have several subsystem managers for various uses, for example:

AudioManagerCollisionManagerInputManageretc.

At first I wanted them to be all singletons, however now want to make the architecture a little bit cleaner. The main idea is to use only one big singleton (for example System) and it will contain all of these objects.

So interaction would be like this :

System::getAudioManager()->playSound("Explosion");//Before it was like this// AudioManager::playSound("Explosion");

However, now classes who need to use these "managers" must get access to the instance of the actual class, with singletons I would use just an include to a file which is needed:

#include "AudioManager.hpp"

Now I have to make this:

#include "System.hpp"

It means that I have to include the main singleton file which contains all the includes, all the other subsystems created and used. Does it have some overhead (performance) or cons?