In the summer of 1975 while traveling in England with a close friend, he met Peter Bardens of the band Camel and producer Alan Tarney, both of whom he would work with in later years.

During his tenure with Worldwide, Eddinger created and directed regional promotional campaigns for over 30 artists including Aretha Franklin, Fleetwood Mac, Toto, Van Halen, David Bowie, Grateful Dead, Journey, AC/DC and Heart.

Eddinger's original synthesizer programs have been used on thousands of recordings by artists including Michael Jackson, Celine Dion, Elton John, Stevie Wonder, Peter Gabriel, Herbie Hancock, Bryan Ferry, and Oasis.

Over the past four plus decades his programs and samples have resided in keyboards and synthesizers manufactured by companies including New England Digital (Synclavier II), Moog, Oberheim, Kurzweil, Yamaha, ARP, and Roland.

Eddinger has played on more than 1,000 recordings by artists including Blues Traveler, Londonbeat, Butthole Surfers, Luciano Pavarotti, Bakers Pink, and Bill Champlin.

He has also performed on several U.S. and World tours with artists including Diana Ross, Sammy Davis Jr., Cliff Richard, Chaka Kahn, Be-Bop Deluxe and Nazareth.

He has produced over 35 albums, has written over 1,000 songs, and his music and productions have appeared on soundtracks for films including Silverado, Empire of the Sun and Celebrity.

For his contributions as a musician, producer, arranger, programmer and industry executive, Eddinger has been the recipient of RIAA Gold and Platinum Awards commemorating the sales of over 50 million albums.

These parties were regularly attended by celebrities of the music, film, television and sports world, and were followed by New York reporters including Joanna Molloy, Richard Johnson, and Flo Anthony.

In April 2011, Eddinger accepted the position as Director of North American Operations for AudiofreaksMusic,[14] a London-based music company specializing in promotion, management, production, publishing and licensing.

[15] Mark is also North American Business Affairs Manager for GoMusicSolutions,[16] a highly successful Galactic Media Company specializing in International promotion and licensing campaigns for new and established artists in the pop, dance and club music genres.