I want to build myself a simple, passive, "volume box" meaning just a pot in a box that I would use to fine tune my stage volume (or allow me to have some volume "in reserve" by doing soundcheck with it set at75% or so). Either if I use it in the effects loop or in front of the amp, the box would most likely have some sort of buffer before it (pedal or dedicated unit). What would be the best value of pot to use to minimize tone loss? Low like 10K or 25K Ohm or as high as 1MEG? Does it make any difference with the buffer in front? Thanks!