Experimented a bit more with this tonight. I severed the PIN1 wire and hard wired my FX RETURN signal to PIN1 so I wouldn't have to have the chassis open and alligator wires jumper it. Here's my observations:
* Opted for a BOSS LS-2 with the level slightly boosted to make up for the slightly dropped signal I've observed running a passive bass through a BOSS buffer instead of directly through the 1/4" on the GK controller
* In GUITAR MODE even though I've wired it to PIN1 which should be STRING1 (high E) neither a piccolo bass, nor a regular strung bass triggers PCM well. Barely at all, actually. Even though SENS is reading levels well, normal pickup is coming through clearly, PCM simply is unusable.
* Simply swapping the GK SETTING > PU DIRECTION = REVERSE assigns my PIN1 signal to STRING 6 and magically everything is triggering great. I get the almost the full range of a 4 string piccolo bass triggering PCM (open low E through A# 14th fret G string), and a slightly reduced range of a regular strung bass from C (3rd fret A string) to A (13th fret G string). Note this is still GUITAR MODE. I'm not exactly sure what conclusions you can draw from this, but apparently that there's different processing on each of the strings and a somewhat fixed range of note tracking as opposed to identical pitch/PCM triggering algorithms on each of the 6 strings. At least that's what I'm getting from this exercise thus far. This took me a while to figure out, the problem is that my regular strung bass has the pickup physically reverse and a matching GK setting, but my piccolo is setup with normal orientation, with it's own GK setting. Confusing seeing the SENS levels high but absolutely nothing on VELOCITY. Serious head scratcher.
* MODELLING > WAVE SYNTH has the same effective range.
* MODELLING sounds general poor or unusable with either instrument, but with the regular strung bass in particular since the bass/bass synth modelling is octave shifted and sounds terrible shifted back up +1 octave. I tried briefly adjusting the GK settings with no immediate success. Run the same instrument through the GK controller and instant modelling greatness. Always fun to run the piccolo bass with guitar/sitar/banjo modelling, though the bass models sound really bad IMO, at least with the piccolo bass, which is very ironic.
* Of course NORMAL PICKUP works great regardless.
* Portamento is crazy since you're pushing every note through the same string so it thinks you're doing seriously wild same-string note jumps and portamento gets applied all of the time.
I currently only use PCM only 90% of the time and NORMAL PICKUP 10% of the time. So I wouldn't miss the modelling. And I wouldn't likely miss the polyphonic aspect with the exception of PCM string splits. But I think running non-GK into the unit holds a lot of promise for me, personally. Forces the unit to work as a "normal" bass synth pedal, plus a regular multi-effects.
I've acquired the resistors that will theoretically force a simulated fully open GK controller volume, but haven't had time to experiment with it yet. I'm ever so slightly nervous feeding 7V to the wrong pin and frying something as I've utterly voided my warranty at this point.
Sorry, no new sound clips yet.