These use the configuration aAmin = aAmax = 0 to determine the max value of samples that offers the best quality.
The max value for ibl samples is 512.
The max value for sunsky samples is 512.
The max value for path samples is 512.
For sunsky samples and path samples, quality is inherent to the value of aAmax.
As the sunflow doc suggests, the max samples value is divided by the corresponding number of samples (aAmin = aAmax).
You can use the PVR-1.4 beta version to test these changes as well as the minimum night brightness .