Shure are a reputable company, without a doubt, but this X2u product is a new one on me. I've had a look around the Shure website and I can't find any mention of being able to use this device with ASIO drivers.
Is the X2u the only interface you use? Just curious. It's not a particularly that great is it. I know you may be on a limited budget but I think you may be barking up the wrong tree with this one.
When you go to your preferences in X1, for playback and recording, do you not see the X2u as an available device?
If you can afford to get some new hardware then I would heartily recommend getting a Roland QUAD-CAPTURE, which is what I use with my laptop setup and it works a treat.