I am experimenting with some image maps from Andrew Price's Poliigon site, I am comparing two colour images for the diffuse texture, a 1k and a 3k, but I can't see any difference, surely I should get better results with a higher resolution image:
The node setup:
The image texture size - this is for the 3k image:
The render settings:
Output from the 3k image texture:
Output from the 1k image texture: