Gravy is an adjective. It means its all good lolol. (At the very least)
A cp251 will allow you to introduce noise to the filter or pitch of an Osc. You can do some neat stuff with the LFOS, sample and hold and lag processor and send those to the destinations on the voyager.
It is best if you have other FOogers to use and even better when you have the Vx351.
If you get a Voyager and CP251 then certianly there will be other CV gear in your future.
Eric
