Presumably, when you adjust the various settings for a particular driver in GPO standalone (on the Audio Setup--->Soundcard tab), the settings propagate to Personal Orchestra Studio?

I ask because I've been messing around with DirectSound latency and haven't noticed anything different when using POS, even varying it between the extremes.

(in case anyone's wondering why I'm using DirectSound drivers, I can't get below 23ms latency with ASIO, even using ASIO4ALL. Knocking back the buffer size gives around 6ms, but the results are unacceptable...)