Females:

Barbra Streisand
Anita Baker
Whitney Houston
Mariah Carey
Celine Dion
Toni Braxton

Males:

Michael McDonald
James Ingram
Michael Bolton
Jon Secada
Meatloaf
Brian McKnight

what exactly do you mean by "powerhouse" - it seems kind of ambiguous by your examples

for pure vocal power - who can belt it out the loudest and most powerful, I think of Aretha Franklin, Annie Lennox, Ella Fitzgerald, PJ Harvey, and Ann Wilson, and Rob Halford, Tom Jones, and Freddie Mercury

Female:

Alison Krauss
LeAnn Rimes
Tanya Tucker

Male:

James Otto (The link in my signature will take you to a great example of how strong and sexy sounding his voice is!) :eyes: :eyes: :eyes:

God bless you and my favorites always!!! :) :) :)

Holly (a day one fan of LeAnn)

Far and away, Martina McBride.