Quick Reply
Dear Dave,
You sound like a nice guy and nobody else seems to want to reply so here go's.
My guess is that maybe only good quality speakers are made with the lower impedience eg. 4 ohms so yourv'e gotta a winna there mate! And maybe nobody has heard of the brand Diff so thats why theres been no reply.
I would also take a guess that maybe no amp is the same so don't worry about different levels of sound settings on your display.
As for sucking the life out of your amp, you only paid $2000.00 Australian for it so what are you complainging about. Don't be a tight bum and buy another one if it blows up. (It's not as if you sourced expert help for it or something)
As for your friend with that weak little amp, I would piss him right off and get a new friend with real equipment like yours or better.
I think I have answered all your questions. Feel free to ask anything else and I would be glad to reply. It's great that we can answer those questions for those new comers to our board.