The Wolcott amp is another option, but the one time I heard it with Merlin VSM loudspeakers, it did not sound musical, IMO.
Also, Supratek Mondeuse 100wpc KT88 monos are designed to be used with low impedance amps, but I have never heard one, and when I have asked in these threads about user experiences, I have received nothing but crickets chirping...