I've populated the PCB's that are designed to accept balanced input and the input/outputs are socketed to allow easy transfer between projects. It took a bit of head scratching, but I managed to find some stock sockets that could be modified to fit the hole pattern on the PCB's. I had to use Takman 1% metal film resistors as the PRP I liked are not being restocked at HiFi Collective. The terminal blocks are to allow a qwick change of resistors when I come to balance the output levels for the amplifiers/drivers requirements. I will start with pots then measure the values and use fixed resistors, this way I can do some final tweaking of the resistor values, if required, without having to unsolder anything.