Blood, Sweat & Tears
Blood, Sweat & Tears 
After their fantastic debut album which established them as a pioneering band, Blood, Sweat & Tears lost their leader when keyboardist/lead vocalist Al Kooper departed (he went on to have an illustrious career as both a producer and solo artist). The group's trumpeters Randy Brecker and Jerry Weiss also left at this point, so the remaining members had to seriously rebuild the band if they were to continue.
In the end they brought in Canadian David Clayton-Thomas as their lead vocalist, who proved to give the group a much more powerful vocal focus than Kooper had offered (Steve Katz and Bobby Colomby had been wanting to bring in a lead singer and move Kooper to just keyboard and songwriting duties before he had left). Dick Halligan, who had played trombone on the first album, took up most of the keyboard duties in the wake of Kooper's departure.
They also found three new horn players, so that by the summer of 1968 the reconfigured Blood, Sweat & Tears consited of David Clayton-Thomas (vocals), Steve Katz (guitar/harmonica/vocals), Fred Lipsius (alto sax/piano), Dick Halligan (organ/piano/trombone/flute), Lew Soloff (trumpet), Chuck Winfield (trumpet), Jerry Hyman (trombone), Jim Fielder (bass) and Bobby Colomby (drums).
Their second album was self-titled, perhaps to signal that they considered it a new start. Stylistically things changed, moving away the psychedelia-tinged R&B/rock of the Kooper era to a more complex jazz-fusion sound, characterised by lots of intricate arrangements and instrumental virtuosity. However at the same time they were able to weave elements of radio-friendly pop into the mix, so that the album yielded three massive hits - "Spinning Wheel", "And When I Die" and "You've Made Me So Very Happy" all got to #2 when released as singles. The album itself topped the charts.
Its worth noting that with Kooper's departure they lost their principle songwriter, and most of Blood, Sweat & Tears consisted of cover material (including Traffic's "Smiling Phases" and Billie Holiday's "God Bless The Child").
The album was a massive success for the band, getting them much further than the original line-up had managed.
Edited by Hi-Finthen - 8/14/13 at 7:16am