I'm with B2D
everything about Vai says Marshall, Egnater, and Bogner. I don't think the ADA MP1 quite gets his tone.
His tone is pretty open for a high gain sound, and it is very rich. The 5150 never sound that open to me, nor does it sound rich. I have heard some great people sound great thru the 5150, and I give the amp its respect, but my vote is kinda NO.
People and this "it's all in his fingers" junk... just answer the question...dang!
We figured out the whole everything from fingers, to blood type, to barometric pressure, zodiac signs, and speaker cables matters - but can you kinda answer the actual question? I'd love to see you guys on Standardized tests - "uhhh the answer is F: I don't believe there is an answer so I will just BS"