hageir: nope. you're thinking of the vx-351 expander (or vx-351 for rack mount). the cp-251 just has cv i/o and adds an lfo, two attenuators, a multiple, lag processor, sample/hold and a four-way mixer to my ms-20
really comes in handy; even for little things like just attenuating the ultra-loud noise coming from the ms-20. it's also much cheaper (but *slightly* less full featured
) than buying an ms-50.