well, I've read a lot of stuff about the yamaha chips, and also some patents.
Some patents also contained some schematics ... and while thinking about them, I solved
a small problem with some sounds in my emu.
There has been many stuff about the Hunting Phenomena and how they fixed it (using a 32 step shift register in an averaging circuit) ... this should work like a low-pass. (They seem to use this shift-register-averaging circuit on everything: operator outputs, feedback, phase modulation input)
So I've implemented another (right now integer) leaky-integrator inside the PM path and voila: sounds just like my AWE64^^