I just heard the intro to the new In Search of Sunrise set, number 7. It starts off really smooth with a track by Banyan Tree, and breaks really smoothly into "Wasted," by Andy Duguid and Leah. First off - neither of the tracks are that great. The first track is a pretty ordinary, and "Wasted" isn't as good as Andy Duguid's and Leah's last collaboration, "Don't Belong."
What does get you though, is the seamless transitioning. Leah's vocals and the rhythm of the track pull in at just the right time, just as the opening track fades out. It comes in gently, and then after you're used to Leah's voice and you get a feel for the rhythm, the bass finally kicks in.
And that's what I love about Tiesto. He's a great DJ, and I've seen (heard) him pull some of the most technical and beautiful transitions. It's great. I wish I could see more of this caliber.