hi man from argentina (bad english), i make this preamp and its a killer amp, tested and verified, the best part is the hi gain channel, the clean one its also very good, i have the pcb on expresspcb, i tried make it as a stompbox and with a 7660 doubling the voltage it work but its better 15v simetrical, i leave you the thing ig you want to build it, here at argentina i workdoing this, amps and stompboxes, so i tried alot of things, and also make my own pcbs, in the schematic  i leave behind the effect loop footswitch  and reverb, just the both channels and buffers saludos.