What is the hardest solo piece for the oboe?

Question:

What is the hardest solo piece for the oboe?

I'm asking Oboists, so if you're not one, please don't answer.

I'm also looking for pieces that aren't so obscure that only a handful of people have heard of it, like the Dolin Psalmody, which while it is quite difficult, is also something I doubt any of you have ever heard of before. If I'm mistaken, let me know.

I'm learning the Vaughan Williams Concerto right now, and it's the hardest piece I've ever tried (and the most beautiful), but I can't imagine that I would have hit the top of the Oboe field while I'm still a ways before graduating from college, so I'm wondering what is the top.

Best Answer - Chosen by Asker: I'm not an oboist. I heard a lot of oboe music at conservatory, however.

The hardest piece for solo oboe (not quite your question, but anyways) that I heard there was Berio's Sequenza VII. It's really tough, requiring absolute technical mastery of the instrument and understanding Berio's unusual compositional approach.

The most beautiful oboe "solo" that I heard while in school was Ravel's "Le Tombeau de Couperin."

Sequenza VII for solo oboe (1969)
Sequenza VII is inhabited by a sort of permanent conflict - for me a very expressive and sometimes dramatic one - between the extreme velocity of the instrumental articulations and the slowness of the musical processes that sustain the work??s progress, such as a certain fixedness of registers, the prolonged absence of certain notes and the increasingly insistent presence of certain intervals (the perfect fifth, for example, which is not without memories of the cor anglais in Tristan).
With Sequenza VII (as with the Sequenzas for flute, trombone, clarinet, trumpet, and bassoon) I continue my search for a virtual polyphony. In this Sequenza the solo part is placed in perspective, as it were ??analyzed?? by the constant presence of a ??tonic,?? a B natural, that may be played, pianissimo, by any other instrument off stage. Sequenza VII was written in 1969 for Heinz Holliger.
- Luciano Berio