In the late 1960s, Walden dropped out of school, quit his job, and devoted his energies to the guitar full-time, picking up a bass player (Al Roberts) and drummer (Randy Reeder) to form a three-piece band named Aphrodite. They started touring and wound up in Denver, playing local clubs and opening for acts like Buddy Miles. It was in Denver that Emerson, Lake & Palmer's manager, Neville Chesters, saw them in a club and offered them a recording contract with ELP's label, Manticore. In 1972, the group moved to England and was reformed, keeping Al Roberts and changing the name to Stray Dog. There, they were signed to Manticore and Greg Lake produced three songs from their first album "Stray Dog". The new group toured with ELP as the opening act, but never really took flight, and eventually folded. Following the breakup of the band, Walden supplanted the ailing Paul Kossoff by providing guitar tracks for Free's final album "Heartbreaker", which was released in 1973 (Walden plays on 'Common Mortal Man', 'Easy on My Soul' and 'Seven Angels'). He also played electric guitar in 1973, on the debut solo album "Still" by King Crimson lyricist, Peter Sinfield. In 1975, he joined The Eric Burdon Band and performed with them for a year.