Help on increasing detail on low poly

[genesis1]

I've followed a lot of tuts on things like this but still have problems.
Recently I downloaded a photo realistic head model. The model itself was pretty low poly but the textures and normal map were 4k maps which gave great detail of the skin texture.
So with that in mind, I created 2 versions of my own model in zbrush. One high and one low poly. I imported the low poly into substance painter and baked the high poly detail to it.
However, the high poly detail was still a bit blurred on the low poly, so I upped the polycount to improve the detail and then exported.
The problem and question I have is this. I find my model is still a lot higher polycount to get enough detail, yet a demo head I downloaded was very low poly with still high detail.
How is this achieved? I'm finding a very low poly cannot preserve enough detail even when I use 4k or 8k maps.

[BeeVee]

Are you using normal maps?

B

[genesis1]

Are you using normal maps?

B

Yes, I'm using 4k Normal maps.

[sami]

Yes, I'm using 4k Normal maps.

3DCoat can help with this. It can generate cavitation and ambient occlusion maps, from geometry, and can help with having really nice normals on the UV maps to have good detail. Then you also want a good bake from a high poly sculpted model to your low poly proxy. Some of the issue is making sure that your UV maps are really good with enough pixel detail too - though this may be less possible with game assets if you have to combine UV maps for performance. Post some pics and what the trouble is and maybe that will help figure out what the issues you're having is.