I had listened to the original Shearwaters on several occasions some years back at a local dealer. The different amps each time I visited were VTL ST-85's, Mesa tube integrated switched to Triode (20w), Although the room was somewhat problematic(terrible design for a demo room) Either amp drove them very nicely, even the low watt mesa.
The best sound produced by these speakers though was in another room/system and driven by a Plinius SA 100Mk11. They really sang and completely dissapeared, and still had the nice tonal balance of the tubes.