Portable Churches can now have a pipe organ that rivals and exceeds the sound quality of permanently installed organs.  St. James in San Jose sets up their "pipe organ" in 5 minutes.  The following explanation of how to do this comes with a warning.  You will want to upgrade your sound system to take full advantage of the software.  St. James has 18" JBL subwoofers to reproduce the low notes of the organ! Have a listen and look at the software controlls in the Hauptwerk Software.

To implement this software, St James uses a digital keyboard with a midi out that plugs into a MacBook Pro using a midi to usb cable. The computer is connected to the sound system through an Apogee Duet. The computer connects to the Duet with a firewire cable. The Duet comes with a break out cable, that provides 1/4" connectors.  Using standard 1/4" cables the Duet is run through two DI boxes and then into two channels on the sound board.  One channel is panned right and the other channel is panned left creating a stereo sound field.

The result is an amazingly authentic organ sound that will greatly exceed people's expectations.  The cost for the software varies between $300 - $600 and the Apogee Duet costs around $600.  A free demo version of the software is available on the Hauptwek site.