Why VAC doesn route output of Roland VSC-xx, Yamaha S-YXGxx?
A 04: VAC simulates plain MME Wave device, which has Wave In and Wave Out ports. If application allows to explicitly assign its output to given Out port, then this port can be VAC’s. Some apps and many soft synths implicitly routes its output to preferred system Wave/DirectSound Out port; in most cases it is a hardware sound card. Try to set the preferred system audio playback device (Control Panel -> Multimedia -> Audio) to the VAC Out port.