What prompted the change to the 12AU7 in the Eros 2 shunt regulator? Can I still use the 12BH7 that used to occupy that spot in the original Eros Phono? The shunt circuit has now gone from 6CG7 to 12BH7 to 12AU7 over the life of the circuit. They're all similar, but the plate dissipation limit is definitely lower for the 12AU7.