[2] The Blues Foundation described Kappus as "the kind of manager and booking agent any musician would want" and "one of the most respected men in the business.
After signing Mike Bloomfield, John Hiatt and Eddie Harris on the first day of the new business,[3] the agency grew to book about 2000 shows a year worldwide for its 30+ artists.
Over the years Kappus helped launch careers for Los Lobos, Robert Cray, Ben Harper, George Thorogood & The Destroyers, John Hiatt, the Neville Brothers, and Trombone Shorty, whilst helping to raise the profile of veteran artists such as Allen Toussaint, Captain Beefheart, Muddy Waters, the Staple Singers, the Blind Boys of Alabama, Albert Collins, and John Lee Hooker.
[11] In his role as a music manager, Kappus has worked for Hooker, Cray, Hiatt, John P. Hammond, the Dirty Dozen Brass Band, Duke Robillard, Loudon Wainwright III, and represented J. J. Cale for thirty years until the latter's death in 2013.
As head of the Rosebud Agency, Kappus incorporated environmental policies and social responsibility issues, which saw the company offices fully converting to solar power in 2000.
[3][18][19] Kappus' environmental concerns also drove him to coordinate two compilations for non-profit, Earthjustice, featuring artists from Tom Waits and Willie Nelson to Norah Jones, Tina Turner, Bob Dylan, Rubén Blades, Michael Franti, Ani DiFranco, Keb Mo, Ruth Brown, Lou Reed and Etta James.
[2] In 2022, Rosebud completed its transfer of over 250,000 items to the University of North Carolina at Chapel Hill's Southern Folklife Collection archives.
[22] In addition to naming Kappus 'Manager / Agent of the Year' four times, Kappus was chosen to induct Eric Clapton (2015), Elvin Bishop (2016), Mavis Staples (2017), Pops Staples (2018), and Bettye Lavette in 2022,[23] as well as inducting John Lee Hooker's The Real Folk Blues album, into the Blues Hall of Fame.
Highlights of the Rosebud Agency and Kappus' history were presented in a featured exhibit at the Blues Hall of Fame, which ran from May 2017 until March 2018.