A Scottish/Irish influenced female voice is as close to angelic as humanly possible, and Eva Cassidy is/was one the purist.
She completely draws you in as you listen. A rare quality.
Yes, Eva Cassidy does have that draw-you-in quality.
There are some other singers with that quality, though having voices far, far afield from a pure sound. To me, some of the best performances come from the worst sounding voices. Not all of their songs - but a few can tear at your heart. Tom Waits’ singing “Soldier’s Things”; John Cash singing “Hurt”. As you said, straight from the heart.
Loreena McKennitt is another with that purity of sound, though she doesn’t have the earthy emotion of Eva Cassidy. Many of McKennitt’s compositions are a marriage of the Scottish/Irish influence with a middle eastern flavor. One of her most moving pieces is “Dante’s Prayer” - about her fiance who drowned.
Another performer who completely stuns me is that 10-year old child, Jackie Evancho. I compared her singing of “O Mio Babbino Caro” to the You Tube clips of every established opera singer performing it, and was amazed-to-goose bumps that the quality of her emotion and expression surpasses all of them. She lilts into the high notes with pure grace - no slur, no hesitation, none of that subtle yet sudden mini-burst of volume the pros exhibit with their universal aura of “I hope I make it”. The little girl still sings with pure emotion, rather than “performing” Mio Babbino, as the pros do. Pretty amazing.