It is well known amongst classical music aficionados that the principal violinist will often dazzle audiences by playing with seeming though every note will have been rehearsed countless times and with unwavering focus.

abandon

Explanation:

"Abandon" is a term that refers to the spontaneous action of an artists. When the artist decides to use "abandon" it means that he has decided to express himself spontaneously, and may even seem random, to express some strong and uncontrollable feeling. When a violinist decides to use this technique, the listener has the impression that the violinist is playing at random to show how his soul is at that moment, but the violinist is playing a piece that has been very well rehearsed many times.