Latest driver of Z-series (Dated March 4th, 2013) support ASIO. Good news from Creative, finally they don't deny ASIO. I'm listening to my favorites songs with Creative ASIO.
With budget of $100-150, if you are a fan of Creative, Soundblaster Z is a good choice (Zx share the same board with Z, it has a separate volume control module than Z). Z-series are the latest product which are fully support in terms of technical assistance, drivers and replacement. Regarding to audio quality, due to all-in-one product, I think quality is average in comparison with other brandname. However, if you use it for gaming, music and movies, Z is a good choice. If you can afford the Fiio E9/E17, it would be good choice for music and Z will play the role in movies/gaming.