Just a reminder that even with attenuation, you will still want to monitor the meters on the R-09, while adjusting levels on the V3. With the appropriate amount of attenuation the meters will be significantly closer to matching each other. You won't want to max-out the meters on either machine, but the one on the R-09 reflects the actual recording level seen by the ADC and has a far less-wide range of what would be considered "acceptible" than whatever is happening on the V3's meter.
If you get the degree of attenuation close to optimal, the meters will be close enough to each other so that you can monitor the easier to read V3 meter instead of the R-09 while recording, but you should still double check when setting up to make sure the R-09 does not peak before the V3 does.