Zack Demos, who began his own music production company under the name Mute City Music in 2015, is a composer/arranger, multi-instrumentalist, and bandleader based in Denver, CO. He is the director and lead arranger for Nostal-jazz, Denver's premier Jazz cover band, playing the soundtracks of retro video games, TV theme songs, and blockbuster films of the past few decades. During football season, Zack plays trombone for the Denver Broncos' Stampede brass band and occasionally arranges music for the group to perform on gameday and at events year-round. He's also a former member as both a drummer and trombone player of the Colorado Avalanche Celly Squad which disbanded prior to the 2025-2026 season. Zack's most recent project is playing the trombone parts of James Pankow in Colorado Transit Authority (CoTA), a tribute to the music of Chicago, which recently performed two sold out shows at Denver's Federal Theater and Oriental Theater

Zack is formerly a fleet arranger and performer for Princess Cruises and their various musical entertainment programs, including a specially licensed version of NBC's "The Voice". Studio work includes being a trombonist/composer on Hang Time (Tapestry/Capri Records), the 2nd CD released by the Colorado Conservatory for the Jazz Arts alumni, directed by renowned Jazz artists Paul Romaine, Greg Gisbert, and Eric Gunnison. Zack was also the composer for Unvented, a short-form sci-fi/comedy web series, and the creator and host of a well-reviewed podcast called "The Soundtrack" where he discussed music in film, television, and video games. Winner of the 2012 UNC Jazz composition contest, Zack composes Big Band music for all skill levels, and those charts are available through Sheet Music Plus, J.W.Pepper, and UNC Jazz Press. He is currently concentrating his efforts toward library music and other multimedia projects

Zack has performed with several high profile artists such as rapper Flo Rida, and has made frequent appearances both as a bandleader and sideman at the critically acclaimed Dazzle, Brown Palace, and 89.3 KUVO's new Masterpiece Studio. Zack has also had the pleasure of performing in the pit orchestras for Joseph and the Amazing Technicolor Dreamcoat (drums) and Urinetown (trombone) both with Stage Flight Theatre. He was also recognized as an outstanding soloist (trombone) at the Metro State University Jazz Festival in 2010. With his high school, Mountain Vista, he had the honor of performing at Carnegie Hall in New York and in the Saint Patrick’s Day Parade in Dublin, Ireland

Zack graduated from the University of Northern Colorado in 2014 where he studied Jazz composition/arranging with Erik Applegate and Kerry Marsh and obtained a degree in Music Business. Now a private instructor, he teaches part-time independently and has limited space available for trombone and drumset students