Howdy Erwin,
I have GPO, and Composer recognizes it as its own device, no strings (or cables) attached
Composer will actually recognize GPO as 8 different devices, because the "GPO Studio" that comes up for such applications has 8 players, with 8 "slots" (for instruments) each. So you have up to 64 spaces for instruments - woohoo! The only thing you have to be careful of is that you have sufficient memory. Garritan recommends a minimum of 1 Gb. I used to have only 512 Mb in my machine, and I could run up to about 4 or 5 instruments, but after that it got "hiccups" really bad. I now have 1.5 Gb of memory, and haven't had any problems even with a whole orchestra loaded. Ahhhh, yes
If you have any other questions about GPO, I'd be glad to help if I can - it's a terrific sound library, and with the recent updates, it's been made even more flexible. It's a very good fit with Composer and especially with the "Pro" version that Mark is going to be releasing.
ttfn,
Sherry