Yafaray clears noise more effectively if you use at least 2 for Samples and for Additional Samples.
Reduce the Threshold value to 0.003 or slightly less and use more passes. It is ok to use more passes than you need as you can cancel the render when it looks clean enough. You really only need a large number of initial samples if there are a lot of small details.
Try setting 20 passes at 4 Samples and 2 Additional samples, with threshold 0.003. That will give 4+38=42 samples which is slightly more than your 32+1. It will finish the first pass much sooner and should clear quite quickly too, as it is re-sampling more pixels at a higher rate.
Nice light btw. You see a lot of V-Ray renders with a similar look.