A few things..
First, DA lenses in my experience tend to have a stronger red and blue channel. Meaning, reds and blues really pop with DA lenses. However, this pop is bad when dealing with noise. First rule, don't use a DA lens for high ISO work.
Second, use your sharpest lens possible, preferably a cold lens. Meaning, a lens that tends to produce images a little on the colder side. As in my case I used the Viv S1 105mm.
Third, when dealing with JPG's straight from the camera do the following. Reduce the saturation all the way and reduce the contrast some (you'll see that doing so does not have as much effect on the resulting image as you might think - look at my two up there)..
That's pretty much it. As you can see you can get great images straight from the camera without noise ninja or any other processing. Again, those two images are straight from the camera.
Last trick..
With the K10D or ANY Pentax camera that has a multiple-exposure feature you can use that to further reduce the noise. Obviously this is not an option for all photos but for static scenes it's the best thing going. Remember, shoot in JPG mode, reduce saturation -3, contrast -2 or -3. Also, make sure the color mode is normal, not bright.. Set the camera to multi-exposure mode to take 2 exposures. Take the two shots (steady on a tripod is always best), let the camera merge the two shots and enjoy your nearly noise free ISO 1600 images..
I never did understand all the complaining about the K10D and it's ISO 1600 performance.. lol - I can't imagine what I could get away with if I used a K20D...