I haven't used the Philips card myself, but a write-up of it claims "The Sonic Edge features the new Sound Agent 2 visual user interface for state of the art features and ultimate sound control." (http://www.dealtime.com/xPR-Philips-Sonic-Edge-5-1-PSC605
In Windows, the Wave Device is the generic driver for playing Windows PCM (.wav) files, which merely provides the function for PCM data to be handled. The Philips Wave Device presumably is the equivalent basic driver supplied to operate the Philips card.
Sound Agent 2 is the "bells & whistles" driver that enables access to the full functionality of the card.
At the moment, MIDI is set to play the Windows Roland GS compatible software wavetable synth sounds. If you select the MPU-401, MIDI will be sent to either an onboard wavetable synth if the card has one, or an external MIDI instrument connected to the MIDI (joystick port) interface.