Well, I've got both the GG Underwater and the GG Amphibians (2 - an OBN set and one I modified)......all three leave something to be desired with volume..... put the Amphibians on the Excalibur and your darn near need earplugs due to the loudness....That is the only time I need to adjust the volume on the Amphibians.... I turn it down on the Excal and max it out on the CTX.
On windy days with the CTX I struggle to hear the Threshold which I am running at 40, volume is maxed at 30 and volume gain I vary due to ambient noise conditions....I prefer to run at 15 to help determine shallow and deep targets but on windy days, I max it out too.
Cliff