Sedi wrote:
Glad I could help

. Unfortunately my teacher taught me the "thin-lipped-high-tension" embouchure that I try to get rid off at the moment. Sometimes I succeed, sometimes I don't. Old habits are hard to break.
Well, you're lucky in that at least you have a concrete idea as to how to go about it; I stumbled across it by accident, basically. I mean, I vaguely knew the concept was out there, and based on technique I observed in the players I wanted to emulate, and on opinions that recommended the relaxed embouchure and its effortlessness, it made sense to me as a higher approach and therefore as a goal, but I had no real idea what it meant in practice or how to get there. So in the meantime force and struggle was the way, until the time ripened for me to just let it all go, like snow slipping off a leaf.
As is probably evident by now, I never really had a teacher. Perhaps it was not knowing how to have a relaxed embouchure that made the transformation so complete for me, because once manifested, it was firmly in place. The difference was so stark that, as I mentioned, there was no going back. But I think it's better to have signposts, as you do, because having them would probably have saved me some time.
What hasn't been mentioned is how little air pressure it takes to separate the lips, and this is key. Once the relaxed embouchure is down, it takes hardly any more air pressure than that to get a big sound, if that's what you want. It goes a long way in eliminating hiss, too, because you no longer blow; you breathe.