for the future, just try this:
start with the settings
-hardware switches on the backside:
[AGC] off
[low cut] off
[mic gain] low
Then see if you can get levels up to -12 ... -6 dB without turning the input level too high. Only switch [mic gain] to "high", if you really need that gain. Recording rather loud things in the "high" mode can lead to problems in form of overloading the input stage.
If you feel that there might be too much bass around on the show dont hesitate to turn [low cut] on. It will help to reduce the probability of overloading the R09s input stage by recording unnecessary loud bass frequencies.