PSW, thanks, for extended explanation.
Yes I am seeking for organ like sound or any other that’s different from what I have now; It may not be very clean and so not much sustained. I did not built many circuits, just read entry level electronics books. According to them one may build a good, low voltage, low current, amplifier with CMOS invertors (just use 3 of inverters), and 1-2, outside resistor and capacitors. Some chips designed to drive old TTL logic and have output current of 10mA, that’s more then enough.
The waveform of oscillating string is not pure sine wave. So even 10% of harmonics distortion will not spoil the sound that much. So it’s really feasible to build onboard “clean” amplifier with CMOS logic.
Hex phonic sound is really cool thing that should be simple with CMOS chips and minimalistic circuitry. As it was noted by fookgub the problem is inter modulaton of string notes. As I build few power amps I know its a problem. And one channel circuits have this inherent – the inter modulation, as soon a there is nonlinearity in the signal channel or compressor pedal or somewhere.
Seems I am from another school of guitar builders, I really do not see beauty of 1 channel (and even 6 channel) sustainers.