The Galactus-sized Audio Research Reference 610T monoblock amplifiers ($20,000/ea) put out 600W. They require 8 matched pairs of 6550C output tubes, one 6550c regulator, one 6H30 as an amplifier regulator, a pair of 6550Cs as drivers, two 6NIP input tubes, and a 6H30 follower—that's a ton of tubes.
But man, oh man, did it makes Sonus Faber's Stradivarius sing in the Son or Filtronique room.
Details here.
