I can't comment on the PHY-Ps but a friend has Lowthers in custom cabinets powered by Coincident Frankensteins with 300Bs and it just sounds incredible. Unbelievable tonality, presence and slam for such a small driver. From my limited experience the 300Bs have more bottom end than the EL84s or 6v6 in the Montille, but I'm sure it will still sound pretty sweet.
