I want to know how I can get in touch with specific world renown jazz and classical
musicians for the purpose of hiring them. An example of a jazz musician might be 
McCoy Tyner or Keith Jarrett. For classical someone such as Vladimir Askenazy

I need information that will put me in direct contact with this level of musician
or their managers, agents, reps, etc.

Your question seems somewhat vague in that it's not sure if you want
contact information for just the artists you mentioned or for almost
any artist.  In that case you can contact Musicians' Unions and look
at the artist's websites for the names of agencies that handle
performers/artists to get the specific artist you are looking for and
also do a GOOGLE to find the artist's website which will also have
contact information.

(1) McCOY TYNER
    c/o ABBY HOFFER
    223-1/2 E. 48TH ST.
    NEW YORK, NY 10017

(2) KEITH JARRETT     (visit www.keithjarrett.org)
    c/o STEPHEN CLOUD
    P. O. BOX 474
    SANTA BARBARA, CA 93140

(3) VLADIMIR D. ASHKENAZY
    SAVINKA
    KAPPELISTR 15
    6045 MEGGEN
    SWITZERLAND

Also, call your local library and ask for CELEBRITY ADDRESS DIRECTORIES.

4KEITH (I'm NOT a GOOGLE RESEARCHER)