I know your speakers fairly well. I know this is a fairly basic recommendation but I would check that you have all of your cables connected properly. If you make a mistake hooking them up, your lack of bass can definitely be a result. Assuming you made no mistake, Islandmandan's advice about trying different placements is definitely a good idea. My best guess, though, is that your NAD may not be able to give the Vandersteen's what they need in terms of power. I don't find them too difficult to drive but they do like a little power.
The one thing I can tell you for sure, is that Vandersteen's do have excellent bass. Unless your speakers are damaged in some way, the problem is not likely to be with your speakers. I think it would be a good idea to go try a few thing mentioned in the posts and see if anything helps. Also, if you didn't use the directions that came with the speakers on how to set them up, you really need to do that. You need to use the formula they give you so you know how much back tilt you will need.
I have a lot of experience setting up Vandersteens. Post back with an update. If the problem remains, maybe we can try some other things, as well. Once you get them working properly, you will be very happy you bought them.
The one thing I can tell you for sure, is that Vandersteen's do have excellent bass. Unless your speakers are damaged in some way, the problem is not likely to be with your speakers. I think it would be a good idea to go try a few thing mentioned in the posts and see if anything helps. Also, if you didn't use the directions that came with the speakers on how to set them up, you really need to do that. You need to use the formula they give you so you know how much back tilt you will need.
I have a lot of experience setting up Vandersteens. Post back with an update. If the problem remains, maybe we can try some other things, as well. Once you get them working properly, you will be very happy you bought them.