This could be THE soul reissue of 2018:
https://www.cherryred.co.uk/product/the-staple-singers-for-what-its-worth-the-complete-epic-recordings-1964-1968-3cd-clamshell-boxset/
As I guessed, ESSENTIAL listening. Just the unbelievably powerful live record included would be worth the price of admission alone.
Midway between their beginnings in the gospel circuit and their soul/funk stars era, these recordings are to my ears the cream of the crop of the Staple's output. While I love their Stax stuff, I reckon the standard Memphis soul production somehow diluted the essence of what was truly a unique band, to the point they became just another (great) soul artist. And regarding their Vee Jay previous recordings, I think that the Epic albums take advantage of a better sound without polishing in excess or compromising the raw quality of the music.
In fact, most of the albums in this boxset have a basic backing of bass, vibrato-laden guitar and drums, with the wonderful, urgent harmonies soaring in top of that and a soloist -more often than not Pops or Mavis- giving it all. And man, what Mavis does with her voice here is jaw-dropping, out of this world. Sometimes it almost hurts physically.
Add to that a handful of legendary Pops-penned songs, innovative covers of gospel classics and contemporary folk/rock numbers and you have a winner. Besides, there's an eerie, haunting quality to these tunes that stems in part from the socio-political situation that surrounded them: the fight for the civil rights in which the Staples were so involved. And in part from the fact they represent a timeless crucible of secular (blues, country and soul) and religious music.
Just a word of warning: avoid long shots, this is high graduation holy water.