[radiaL] Monitoring audio input

Hi all-
I've got a PB G4 1.5GHz 1.25GB RAM OSX 10.4.11
Been using Radial for many years loading samples
and playing around and such.
Today I tried running a theremin through Radial (I'm
using an M-Audio FireWire Solo as an interface).
I see I'm getting an input level and indeed the recording is loaded
and will play back fine.

PROBLEM:  Can't seem to monitor the input signal

I'm thinking it's just a setting that I'm missing

Help & thanks

S