I did a quick little testing whether you can get better image quality by processing images before you do an HDR. I used Lightroom, current version as of time of writing is 2.7.
Top part of the testing image is HDR made from images exported out of lightroom, processed at default settings. You can export tiffs from Lightroom or choose the export for photomatix from file menu, result is the same.
Bottom part of the image is an HDR made from original raw files with no processing. Lightroom’s original dng files have of course no processing.
Nothing some sharpening won’t fix. Just make sure you don’t forget to process your HDR’s!