It is easy to load .wav samples with NN-XT..
First of all, make sure your samples are in the right format, if not, I use Nero Wave Editor. I load the sample I want, and just saves it right after, then the samples is in the right format, and you can't hear any difference. I have tried to use Wavelab too, where I transform the bitrate to the right one, but then it sounds like it is smurfs who are talking..
Now you have the sample you want in the right bitrate, then you take your NN-XT, push the triangle in the bottom of your NN-XT, where the text NN-XT REMOTE EDITOR appears..
Now alot of buttons will appear, these are just adjustments for your sample. The "new window", that are shown now, after you pushed the button, in the top left corner there will be a button with the text "Load Sample", I think it says it all.
You will now be able to play your sample with Reason, and another information, Reason puts your sample at the 3 pianosomething.
Happy sampling..
Quark
PS: With NN-19, you just have to push the blue button, then you will be able to load your sample..