To get a better and sharper render move the preset slidet to the Final point. or use custom setings. I attach here a picture of the setings I most use.
In the manual seting are key for sharper pictures:
[u:707f669cc4]Texture filtering[/u:707f669cc4]: this is for reducing noice in distant texture with small pattern or bad textures (I never use it)
[u:707f669cc4]Min shading rate[/u:707f669cc4]: This is key for sharpnes, low values are sharp but slow, hi value are faster but lose details.
[u:707f669cc4]Pixel sample[/u:707f669cc4]: it say how many samples are done for one pixel, 1 won't be antialiasing but fast, something between 3 and 5 are good.
[u:707f669cc4]Max Texture size[/u:707f669cc4]: here a low number will save memory but will lose details.
[u:707f669cc4]Post filter size[/u:707f669cc4]: this is the way firefly handle antialiasing, a hiher number smoth the image. The box filter is fast but blurr too much. The gaussian works better but slower. Never used the Sinc, it's the slower.
Remember to do your own test and save them for later use.
If you need some more help please ask, I'll be very pleased to try to help you