While attending UNLV, he was a member of the acclaimed UNLV Jazz Ensemble where his drumming and arranging skills caught the attention of vocalist Joe Williams. In 1981, at 19 years of age, Dennis moved to New York City and landed a gig as a drummer on Broadway. His Broadway credits include "The First" and "A Chorus Line".
In January of 1983, Dennis joined the Count Basie Orchestra on the personal recommendation of Mr. Williams. He would become the youngest member of the orchestra and the last drummer to be hired by Mr. Basie personally.
Dennis traveled extensively and worked alongside Mr. Basie until his death in April 1984. He continued with the orchestra under the direction of interim leader Eric Dixon followed by Thad Jones. In 1985 under Mr. Jones's leadership, the Count Basie Orchestra recorded one of Dennis's compositions entitled "And That's That".
Dennis stayed with the band, when Frank Foster took over as leader, until December of 1987. Dennis's composition "Bus Dust" was included on the CD "Long Live The Chief" which was recorded during Mr. Foster's tenure as leader.
After leaving the Orchestra, he returned to New York and would soon become the drummer of choice for a number of large ensembles including the American Jazz Orchestra, the Carla Bley Big Band, the Vanguard Jazz Orchestra, Buck Clayton's Swing Band, the Dizzy Gillespie All Star Big Band.
Dennis's transition from sideman to leader continued with his frequent trips to Europe as a guest conductor, arranger and/or soloist for such outstanding ensembles as the Kluvers Big Band in Aarhus, Denmark, the Danish Radio Big Band in Copenhagen, Denmark and the WDR Big Band in Koln, Germany.
In 2010, he returned to the Count Basie Orchestra where he served as it's leader and chief conductor until 2013 and on November 7th 2015, he was named chief conductor of the Jazz Orchestra of the Concertgebouw in Amsterdam, Holland.
In addition to being a seasoned musician, Dennis is also a highly respected composer/arranger whose commissioned works have been recorded by the United States Millitary Academy at West Point's Jazz Knights BIg Band, The Temple University Jazz Ensemble, The Columbus Jazz Orchestra and, most notably, the McCoy Tyner Big Band whose Grammy winning CDs "The Turning Point" and "Journey" included four of Dennis's arrangements.
As an educator, he continues to conduct master classes, seminars, and workshops thoughout Europe, Asia, Canada and the USA. From 2002-2003, Dennis served as a guest professor at the Royal Conservatory in Aarhus, Denmark and from 2012-2013, he was the Visiting Artist in Jazz Studies at the prestigious Eastman School of Music in Rochester, New York
He is currently a professor at Queens College in Flushing, NY and a member of the jazz faculty at the Birch Creek Summer Jazz Camp in Egg Harbor, Wisconsin and the Skidmore Jazz Institute in Saratoga Springs, NY.
Some of the other notable musicians Dennis has performed with include: Monty Alexander, Tony Bennett, Quincy Jones, Hank Jones and Sir George Shearing, who said "If I ever have a record date coming up that calls for a drummer and Dennis is not available, I'll postpone the session. He's that good."