Audio engine is the BASS lib by Un4seen Developments
Beside DirectSound, WASAPI and ASIO are supported.
Hence you can configure MusicBee for bit perfect output.
Some simple DSP functions.
Mono does what is says.
Stereo Enhancer narrows the sound stage. It is probably a cross feed. Nice for headphone listening.
To use VST, an additional plug-in should be installed first.
Download it here: http://getmusicbee.com/addons/plugins/16/vst-effects-support/
Move it to the MusicBee plug-in dir.
No matter what OS you are running (32/64) MusicBee is 32 bit hence you need the X86 version
You should see the VST Host as being active.
You can supply a path the the VST plug-ins you are going to use.
All VTS plug-ins are accessible in the DSP section.
Use the check box to activate, double click to access the parameters.
Isone VST plug-in running in MusicBee