The answer lies in what we can bring to the table using our musical skills. No matter what they are, we all have a unique voice in the way we deliver a 'performance'.
Surely, the only real 'unique sound' could be achieved through improvisation.
This is why I am such a fan of the late Jazz guitarist Derek Bailey. He produced something unique in every performance. How unique? Well, very unique actually because it would be very hard to recreate each performance. And this is the only yardstick with which we can accurately measure uniqueness.
The power of this clip lies in the commitment to creating new sounds but also the genius is in how Derek structures these ideas (seemingly purely random thoughts) into a homogeneous 'musical entity'. So perhaps it was less random than it seems? Perhaps random musical thoughts are subconsciously guided? Remember, a firework has no navigational guidance system but it still goes up and comes down.
Hopefully, it should get you thinking about the sound you/we/I make and to appreciate that sometimes the less obvious the method of sound production, the more powerful the response in the listener.
So many thanks for the ideas contributed in this thread. I have decided to abandon attempts to achieve my unique sound using Omnisphere. Instead I am committed to exploring new ideas through improvisation using my Triton alone and hopefully getting near the 'spirit' of Derek in my future explorations.
As Gene Kranz said: "We knew it was there, we just didn't know how to get there".
All the best,