Musical Design Amplifiers could easily fit into this discussion, although they never advertise so they won't get much play in any of the magazines or AV forums. John Hellig's amps complete well with anything 2-3X their cost.
He is a gifted designer that is not much of a marketer. He has a loyal fan base and stays busy enough through word of mouth.
His stuff is really worth an audition and I think you will find it perform to an equal level or better than some amplifiers in the 5-6K range