Quad preamp notes:

This unit is phantom powered. It is also possible to use a single external battery ( minimum 9v).
This design uses 1:1 transformers to achieve balanced outputs.
Center tapped transformers can also be used.

Power calculations:

For studio and stage applications it is best to use LF356 type opamps, for their inherent stability in driving long (capacitive) cables. However, the power consumption for LF356 is 10mA. TLO71 is in these terms a better choice.

	Current	Voltage	noise

LF356: 10mA	44V	12nVHz-1
TLO81:  2mA	36V	24nVHz-1

If the Phantom voltage is 48V, the LF356 would work on a voltage of maximum 24Volts.
This voltage will be higher when center tapped transformers are used to drive the outputs.