Once I've made sure the op amp of my choice (MCP6002-i/SN) does the job, I've designed a minimal sub-part of my future hexaphonic pickup. The idea was to have an 8-pin connector on the board in the end: 2 pins for ground and power and the rest 6 are signal outputs. This board would be connected to another module, for example a mixer, that mixes 6 channels into 2 for some stereo-effect, or ADC for digital signal output (like those weird Roland synth guitars that have proprietary digital connector), or ADC pins of some microcontroller capable of USB-MIDI, that would track the pitches of every string and return MIDI messages directly.

Every IC has two op amps on board, so I made a two-channel prototype on a third of the board and had 4 connections out of final 8 output pins. After I made some scary sparks, by accidentally shorting power by conductive strings, I've decided to switch from 18650 cell to a humble 9v battery, at least for now, while nothing is really mounted securely.