Dello's greatest success came as a songwriter. His tune "(Do I Still) Figure in Your Life," originally recorded by Honeybus and redone for Into Your Eyes, was covered by Dave Berry, Joe Cocker, and Dana.

Dello initially played with future Honeybus bandmate Ray Cane in a variety of early-'60s rock bands. Forming a group, the Yum Yum Band, with ex-Them drummer Terry Noone, Dello recorded five singles with the band before a collapsed lung forced him to endure a lengthy layoff in early 1966. While recuperating, he gave considerable thought to reuniting with Cane and forming a new band, Honeybus, in 1967.

Forsaking the usually club circuit, Dello and Honeybus primarily focused on studio recordings. They made a few appearances on television or special showcases, using a mellotron to reproduce the overdubbed sounds of their records. Pressured to tour, following the release of Honeybus's only Top Ten hit, "I Can't Let Maggie Go," in April 1968, Dello resigned from the band instead. Replaced by Jim Kelly, Dello devoted himself to studying music theory and learning to play the violin.