It's more effort than putting a banana plug on a 3 core mains, but not much, neither is a hard job. But the difference in volume was large.
I'll dig them out of the box tomo and check if need be, but it worked out at like one quarter turn on my amplifier dial with the Soundlabs. It turns less than 360 degrees from nil to max. So it was a LOT of power lost.
I am running a small amp with very very hungry speakers so the difference might have been upped because of that. But after I spotted what was going on I was most surprised.