Unfortunately there's a bug in the software, which disregards the volume setting. We're working on this issue and it will be fixed in the following upgrade, but until then, I'm afraid your best option is to scale down the volume of the original sound before uploading it to Diamond. You could use Audacity for that - a nice tutorial is here:
http://www.saberforum.com/index.php?topic=11033.0Marius.
Actually, this doesn't work. The software appears to automatically amplify the sound prior to writing to the saber. It normalizes them similar to the default Amplify effect in Audacity - as loud as it'll get without clipping.
I'm trying to write an effect with a quiet idle hum, but it won't let me do it. I've reduce the volume on the source .wav way down, but it still comes out the same. Zalbaag reported this same thing.
If you want to have a smooth transition between effects, this makes it difficult. If I have "tone a" as my idle hum, and "tone b" as my swing, I want the end of the swing to seamlessly melt into the idle hum. But, since the swing has some louder sounds, the background idle in the swing is at a lower volume.
However, I think some of the default effects kind of rely on this. Their waveforms aren't at maximum - the saber amplifies them. If it wasn't for this, the default saber effects would be a lot quieter.
What's needed is a button on the effect editor screen to either
a) amplify sound to max
b) play at actual volume
The default could be (a) so it doesn't affect the sounds that come with the saber.