Well at least my setting is operative (2 x Casio ctk-720 ; Casio MA-150 for the pedalboard (Johannes Rohlf, very nice) ; Speakers Thonet&Wander Stark ; Computer Amilo 1650G with 2Gb Ram and Myorgan, since the last GrandOrgue doesnt works so good (only crakling, blocking) ; OS: XP-SP3 OEM ). I downloaded more or less all VPO-sets.
I love this Stiehr-Mockers but this crackles (ca grésille) when using only 4 stops in G.O. and couplers. With less it doesnt crackles anymore, with more than 4 stops its worse. Of course I think of overloaded RAM, buuuut ->
In revenche, the Burea AGO-extended NOW doesnt seems to have limits, and this is much bigger than Stiehr-Mockers.
I tried to adjust the latency up to 45ms, this is still all ok for keyboard-response. Before, Burea was crackling too, now its fine. Adjusting latency higher doesnt bring nothing more.
Some others organ are crackling too: at least Pitea (my adaptation of the organ-file), but so terrible.
Not crackling: Saint Augustine, Saint Stephen, Wilderwank-demo and harpsichords but they are all more little.
Got a clue?