The OP is using 1 infinite light set @ 500% intensity, a value that, IMHO, is far to excessive for the present condicions.  From the original renders, the floor and railings are too bright, almost washing out the texture details.  You will see this type of condition photographically where two extreme exposures need to be balanced out to an acceptable level.  

One approach would involve making multiple photographic exposures and combine the images creating an HDRI.  Might be possible with Poser but if your renders are exceptionally long, not very feasible.

The second approach would add a fill light to brighten the shadow areas as it is done in Hollywood.  This can easily be done in Poser because the low intensity fill light can be set not to cast shadows, yet produce the necessary illumination without washing out any details.  

And I chose the second approach because it is easier to control different conditions.