I've had Smile Bootlegs for years and years, but I have to say that this new boxset is a complete mind-blower. Brian Wilson's basslines (as played by Carole) are just so unusual. The note choices, the rhythmic spots- I would never in a million years think to have the bass play some of the things he has Carole do. If you have Spotify, check out "Father Of the Man"- actually, here's some of it:
Child is Father of the Man, The Beach Boys SMiLE 1966 new! - YouTube
Really deep, beautoful music and, unlike Pet Sounds where a lot of the bass was doubled and obscured by reverb, the bass is strong and clear on a lot of this.