Yes, I can do that AFTER the loop starts playing but the problem still exists that the loop initially starts playing louder than it is recorded no matter what the playback or overdub volumes are set to. And if I'm overdubbing over an existing CD recording then the volume of that recording will drop when I adjust the volume. For instance I sometimes build up a drum loop with multiple overdubs - getting the balance between high-hat and snare is very difficult if I can't hear the relative volumes when I'm recording.

Sometimes I'm just using the Spider Jam as a looper, feeding the output from a mixer into the CD input. In this situation I would have to adjust the volume after every overdub.

However....I've now realised that the problem only exists if I'm using headphones or the RCA outputs for monitoring which reinforces my stereo/mono theory. If I'm just listening to the speaker then I'm hearing the mono version both as I record and during playback and everything is fine.

If anyone wants to reproduce the problem then record a loop from the CD input at constant volume, using headphones to monitor. As soon as you hit the record button again to start loop playback you should notice a drastic increase in volume.