David Hamilton, who takes the same central role tomorrow, is quite simply "the Southern Hemisphere equivalent of Peter Schreier".
Hamilton and Paczian have teamed up on two previous occasions for St Matthew Passion and the Scottish tenor is an "absolute favourite".
"The most important thing is that he fully understands every word he sings," she explains. "He puts the right amount of drama where it's appropriate and leaves it out in other places."
Paczian is a stickler for using the original text. "Not because it's German but because it's what Bach set to music," she says. "As soon as you start using a second language, you make compromises."
Among the other soloists, Nicola Edgecome just happens to be the conductor's favourite Baroque soprano. "She knows the style," as Paczian puts it. "She's got the lightness, the phrasing and the articulation."
Alto Sarah Court is treasured for her "terrific musical intelligence" which means "she reacts instantly to any suggestions I have to make".
Jared Holt, a former Mobil Song Quest winner who has sung at Covent Garden and Glyndebourne, "was simply stunning at the first piano rehearsal".
Holt has returned to New Zealand and the benefits are ours, Paczian feels. "He easily could have been one of the world's leading basses but he's chosen to come back to Auckland and earn his money as a lawyer."
Anthony Schneider is the youngest Jesus Paczian has worked with. "His is one of the biggest challenges of the work but he's a bright lad. He will probably only be around for this year and then he'll leave for further studies in Europe."
Paczian is very happy with her soloists in what she describes as "one of the greatest choral works of all time. Bach's music speaks for itself, and there's a humanity that comes through in every bar."
One of her favourite moments is a four-bar fragment in which the chorus comes to the realisation that it is dealing with the Son of God.
She is also aware of Bach Musica's loyal audience. "They come," she suggests, "because they can feel that this is true music of the soul."
She has every reason to be proud of the way Bach Musica grew out of the pioneering Bach Cantata Society.
"I've gradually extended the repertoire, lifted the quality and widened that audience. Now we only have professional musicians. Our orchestra is made up of APO players and freelancers."
Yet Paczian always thrills to the magic lift that happens between final rehearsal and performance. "It's amazing. The musicians put everything into it and don't take anything for granted."