The METALLICA / LADY GAGA team-up at the Grammys REALLY worked . . . as long as you overlook the fact that JAMES HETFIELD’s microphone wasn’t working through most of it.

It went so well that LARS ULRICH made it sound like they’d like to collaborate more . . . and he even called her the “quintessential perfect fifth member of this band.” But James does NOT agree apparently.

He was asked about doing something with Gaga in a new interview, and he said, quote, “I have no interest . . . but just being with her gave me a different energy, she goes beyond the limits, like us.” For what it’s worth, the quote was taken from a Chilean source, so maybe something got lost in translation.