Murphy was the secondary songwriter in Soul Asylum, with Dave Pirner responsible for bulk of the band's material. Some of Murphy's solo writing credits include "Can't Go Back" from Made To Be Broken, "Cartoon" off Hang Time and "Gullible's Travels" from And The Horse They Rode In On. Additionally, he and Pirner co-wrote "Easy Street" which appeared on Horse, and he co-wrote "Promises Broken" off Let Your Dim Light Shine with Marc Perlman.
In 1988, Murphy formed Golden Smog, a Minneapolis supergroup made up of members of The Replacements, The Jayhawks and Run Westy Run. Murphy was credited as "David Spear" on the group's debut album, Down By The Old Mainstream, because of contractual obligations.
In 1992, Murphy appeared on the debut solo album by former Replacements drummer Chris Mars, Horseshoes And Hand Grenades.
