I got one of the 13pin-to-audio kenwood cables for the purposes of testing out (other non-S612) audio sources with the filter. Can anyone else attest to this working properly? Here's my experience.
For continuous audio tracks, drum tracks, etc: Works fine, but I got a noticeable noise floor. There is no infinite envelope on the AX-60. Even at it's slowest setting it still starts to taper off the volume after 10 seconds or so, so you either need to hold a key down, or set a fast attack/slow release VCA and turn on the arpeggiator. Not a big deal.
To play/filter another synthesizer: Obviously I had to use the 13pin cable as well as a MIDI cable for anything other than an S612. For this, I got a very high noise floor, but it works. I needed to set the "sampler" fader all the way to "B" so there was no internal AX-60 VCO audible.
To use another synthesizer as a second oscillator: This is where I had some major issues. Still a very high noise floor, and there's something about having audio coming through the 13pin cable that makes the internal oscillators behave very strangely. Volume seems to change randomly from key to key. There is a distortion in both the incoming audio and AX-60 oscillators, so that neither sound very clear. Adjusting the volume on the second synth seemed to change this effect a little, but not correct it. It basically became unusable with the "sampler" fader anywhere other than all the way down to "B".
Does anyone know what the pinout is? Maybe modifying the cable itself by breaking/clipping all of the "extra" pins save the R/L audio and grounds would solve some of the problems. Maybe the audio and ground pins are different in the Kenwood cable too. Maybe rerouting the lugs inside the AX-60 connecting the 13pin jack to 1/4" jacks elsewhere would work better. I'm competent at soldering, but I wouldn't know where to solder the jacks to. Does anyone have any insight? Thanks.