cool tuning trick replacing the ribbon cables (like on right) with single wires......because the design happens to coincidentally split the PCBs at the tube high impedance points, wiggling them around could definitely be a very cool way to tune these model amps since the wires are insulated and most are decoupled audio paths (lesser shock hazard) Also, since they are solid, they would stay (when done wiggling/coupling more so than stranded.....