This is an updated loop design based on feedback with greater transparency and only a send level control to simplify the setup process.
this loop has a 40mm centre to centre jack spacing and is the loop currently used in all Aurora Audio amplifier/preamp builds.
This circuit is powered from the B+ supply and needs 250-400v for optimal operation.
Please note this PCB is not for inexperienced users. You are working with high voltages that are potentially fatal.