The album is a significant musical departure for the band and is the first to feature the Flames' Blondie Chaplin and Ricky Fataar as additions to their official line-up.

[6][nb 1] After Dennis Wilson injured his hand, leaving him unable to play drums for a period, he was substituted onstage by the Flames' Ricky Fataar (and briefly touring musician Mike Kowalski).

"[11] By then, Fataar and the Flames' guitarist Blondie Chaplin were participating in the Beach Boys' recording sessions, and at Carl's and manager Jack Rieley's behest, soon became official members.

[13]On February 29, 1972, the group held a press conference in London, where they announced the new additions in their line-up, as well as the imminent release of the album Smile, which had been shelved since 1967.

[14] Smile was never delivered; Leaf writes that the purpose of the latter announcement may have been to mislead Reprise into allowing the group more time to prepare the album that became Carl and the Passions.

[16] Sessions for the Beach Boys' third Reprise album lasted from December 4, 1971 to April 13, 1972, and were held largely at the band's private studio.

[18] The members worked in three separate factions: Carl, Fataar, and Chaplin; Love and Jardine; and Dennis with touring musician Daryl Dragon.

[20][nb 2] Wilson was absent for most of the sessions, and was more involved with producing the 1972 self-titled debut album by Spring, a collaboration with David Sandler.

"[16] In an interview held shortly after the release of Carl and the Passions, Johnston said: "I spoke to Brian a couple of weeks ago and he told me that he really didn't have too much to do with this album.

[We] branched out and did types of songs that we hadn't done in the past: gospel, some with the sound of a choir, and a couple from Ricky and Blondie that have a rock feel.

[2] "All This Is That" (written by Carl, Jardine, and Love) was inspired by Maharishi Mahesh Yogi's Transcendental Meditation teachings[32] and the Robert Frost poem "The Road Not Taken".

[18] Biographer Mark Dillon writes, "The piano on their groovy cut 'Here She Comes' sounds like Traffic and the harmonies are in the Crosby, Stills and Nash vein.

"[33] Unused tracks include "Oh Sweet Something", "Out in the Country", "Spark in the Dark", "Rooftop Harry", "Body Talk (Grease Job)" and a medley of "Gimme Some Lovin'" / "I Need Your Love", all of which were released on the 2022 compilation Sail On Sailor – 1972.

[34] Bruce Johnston recorded a discarded track, "Ten Years Harmony" [sic], with a re-recording by the supergroup California Music later released in 1974.

[18] Still-unreleased material that was recorded during the album's sessions include "Funky Fever" and a cover version of Stephen Stills' "Change Partners".

[43] According to music historian Keith Badman, the Pet Sounds pairing provoked "an unfavourable comparison with the landmark 1966 LP and contribute[d] to the album stalling [...] in the US charts.

The core members were supported onstage by guitarists Ed Carter and Billy Hinsche, keyboardists Daryl Dragon and Toni Tennille, as well as a horn section and two additional percussionists.

Long-time Beach Boys fans were incensed that two of the eight cuts were by 'outsiders' (Blondie and Ricky), and nobody was particularly stimulated by the preachy tone of the TM tunes.

"[1] Conversely, in his review for The San Diego Door, Cameron Crowe wrote, "So Tough finds some excellent music with no trace of anything left over from the Pet Sounds days.

"[59] Retrospectively, AllMusic's John Bush wrote, "The songwriting was neither as solid as 1970's Sunflower nor as idiosyncratic as 1971's Surf's Up though, and the few fans left from the '60s were undoubtedly turned off – if not by the weak songs, then certainly by the muddy sound.

"[37] He noted that Dennis' contributions were "magnificent epics, explorations of the heart in sound" that showed "his vision was way out of kilter the rest of the band"[2] Among biographers, John Tobler decreed in 1978 that Carl and the Passions was "generally accepted as being the lamest Beach Boy album since the fragmented 20/20 [and] bears the mark of a project with too little thought behind it.

[3] Elton John penned liner notes for the 2000 CD reissue, writing: 'This is an album which I have loved for a long time... Carl and the Passions: So Tough has moments of breathtaking genius and experimentation.