One of the most intense high energy shows I've been to was the Sasha and Digweed performance at the 5050 aka Chad's Warehouse in Seattle. It was the epitome of what trance music should be.
Since I first became acquainted with Tangerine Dream, or even Pink Floyd, and all the way through Burning Man, the idea of mood music has fascinated me. The difference between that kind of music, particularly in its electronica form, and the music, say, that I create, is that it is designed to reflect the moods of the people listening to it (as opposed to the moods of the creator). Either intuitively or through some form of logical reasoning, artists like Paul Oakenfold, John Digweed, and Sasha are able to find the connection between beats and notes and higher order networks in the brain.
The result is describe in words, but ultimately trance, for me, is a Zen-like state where only you (i.e., the self) and the music exist on some Platonic plane. This was an experience I've felt listening to trance and other mood music (Oakenfold, Tangerine Dream, Pink Floyd) while driving through beautiful landscapes, at Burning Man, and now, at the Sasha and Digweed performance. The word "trance" describes the music appropriately.
While it is probably true that psychedelic and other mood-altering substances may provide for a different sort of experience, perhaps one that easily enables a person to reach that Plantonic realm, I don't believe it's necessary at all. In fact, there is always the problem that one may only perceive to be colinear with the music when they are not, under the influence. This is unlikely to happen when your neural networks are pretty much at equilibrium (usually the case). However, it probably does make it more difficult to easily ignore other attention-demanding aspects of your brain without an ability to focus with discipline.
Pretentious stuff. But my attempts to explain trancing in words illustrate my point about the connection I feel to trance, more than the words themselves do.
Anyways, it's very clear that artists who make trance music need a great deal of exposure and a significant connection to the aspects of their brains that can let them relate to the trace-experience. Sasha and Digweed demonstrated that they have it, and if you get a chance to check them out, I definitely recommend it.