Expanding on what Brian is getting at, I'm not sure about the OCM version, but if you have the gains set on a standard V3 so that the preamp is showing appropriate levels on its meters (which accurately reflect the level of the digital output), the analog line-output will be at a quite high output level. Unless attenuated, that high-level analog output level can easily overload the input stage of the following equipment if it's not designed to handle those kinds of levels.
I used to run the V3 analog output without attenuation into the line-input an original R-09, and to avoid overloading the input stage of the R-09 the gain settings on the V3 needed to be set so low they barely registed on the V3 meters. Sounded fine though. With the correct amount of attenuation between the V3 analog output and the R-09 line-in, I could have run the V3 gain higher, which would have made it easier to use the digital out and analog out simultaneously, with appropriate levels to both the digial and analog recorders which followed.
I can't remember- Is there a switch or jumper inside the V3 which attenuates it's analog output voltage?