When sounding out those fundamentals it almost feels like a vibrating massage back into the muscles behind the part of the embouchure that actually touches the mouthpiece. I'm convinced that the embouchure crisis (and the lip callus that came along with it) I had a while back was due to my over using the muscles in the part of the embouchure touching the mouthpiece and under using the muscles in the part of the embouchure (of which I'm much less proprioceptively aware) back behind those front line muscles. I regret letting the band directors of the community band getting me to play first horn (because I was the only one) well before I was actually capable of doing so.
I'm still working with the Brahms Requiem and finding it a wonderful piece of music. Part of it is I think I'm very attracted to playing with voices instead of purely instrumental music. For me, tone is the foundation of music, and blending the horn tone with that of the human voice creates a sound I can't get enough of. Putting on the headphones and playing along with the CD alters my state of mind every single time.
The other thing about the Brahms is the horn writing. I knew his dad was a player of the pre-valve horn. What I hadn't realized was how every single horn phrase in the piece sounds so archetypically horn like. There are all those intervals of the hunting horn put to symphonic use, along with those amazing half steps he uses for emphasis.
Working on the Brahms has also had the effect of crystalizing my thoughts on concert band music, which has always had the feel to me more of etudes than pure music. That the Brahms is way easier to play (just a few high F's and G's and none of those weirdly complex rhythms that are such a staple of band music) and that it's infinitely more beautiful bolsters that notion.