LOL, I'm glad you spelled out the conditions on this one.

I'd better specify what band these people were from, 'cause some go way back!

Vocals: David Clayton Thomas (Blood, Sweat, & Tears)
Guitars: David Gilmore (Pink Floyd) and Kenny Wayne Shepherd
Bass: John Paul Jones (Led Zeppelin)
Drums: Buddy Rich (headlined his own jazz bands)
Keyboards: 'Tone' Hall (Savoy Brown)

These aren't necessarily the best in the world at what they do, but I think the combination would make a killer Blues band!