The setup I am using sounds very much like yours, and also that of RoyKnight in this thread. There is one difference, however, I would like your comments about.
I am also using MacPro bootcamp/XP 64, and have my setup going into 6 dual channels thru an audiofire 12: GT, SW, CH, P, Highs, and a mix-down which goes thru the lexicaon 200 to a 5.1 home theater.
My dual channels are set up in a C/C# alternating note configuration, instead of using stereo channels. I am not very pleased with the whole sound effect. The sound is brash, "in your face", not pleasing and not real integrated. Have you ever used the C/C# configuration for sound output, and if so what led you to choose stereo? I was hoping that the alternating notes would help distribute the sound, but I can't tell much difference.
I realize it could be other factors, like the Organ sample I am using. But listening to your recent recording of the Final of the Vierne Symphone, I was amazed at the great sound.
I assume you used the Hauptwerk recording feature for the sound, so it did not employ your room audio system, so it may not be an appropriate cmparison. You'll probably tell me I should purchase the Metz Organ.
Thanks for any ideas.