What's wrong with the API? And what makes you think that the sound of Jeff Buckley is all due to just the mic preamp?

The API sounds a bit too harsh to me. Or perhaps it's my Studio Projects C1 microphone that's causing that sound. So maybe you could recommend a better mic for my vocals, or perhaps a good mic-preamp combination.

Or perhaps it's my Studio Projects C1 microphone that's causing that sound.

Bingo.

I'm not in tune with who Jeff Buckley is and what his voice is like so I may not be the best person to ask, but the C1 mic is way more likely to be your problem than the API mic pre. What I may like for a mic you might not. You really have to find a way to get a hold some real good mics, not those bedroom toys, and come to your own conclusions.

http://duc.digidesign.com/showflat.php?Number=831979

look for this post in the blog>>>
"If you wanna hear just how great a U87 can sound listen to Jeff Buckley's vocals on the album Grace."

This is just one source of information I heard out here.... Hope it helps and yeah jeff buckley had some great vocals!!! Good luck

(edit) As for preamps used.... research Andy Wallace...
http://duc.digidesign.com/showflat.php?Number=60145 (/edit)

Yah, C1 is most definitely it...i've heard it sound decent on certain vocals, but mostly for more speak-singing types.

For a similar Jeff Buckley voice, check out a group I do graphic design work for, Soulajar.

http://www.myspace.com/soulajar

"Sweet Air" is a track that rings a Buckley nature. They even cover a great version of "Everybody Here Wants You"

Good band. I like that guy's voice. Solid.

Anyway, yeah man the best thing to do is try to get your hands on a few mics and see what sounds best. Maybe find some to rent and see what sounds best.