A software MIDI synthesizer for Windows, which functions as a VSTi plugin. Supports both the Yamaha XG and the Roland GS extensions, which is a unique feature of the S-YXG50. The VSTi was a part of the Yamaha SOL2 package. Yamaha discontinued support of this software synthesizer in 2003. As it is abandonware now, a portable version of the VSTi was created (installation and registry keys are not required). It uses embedded (into DLL resources) official 4MB wavetable files, which is the best version of wavetable files for the S-YXG50.
Download:yamaha_syxg50_vsti.7z (3.0MB).
Scorpius is a great free synth VST plugin that offers you some amazing psychedelic sounds. The interface is not the most intuitive, however it has a vast range of different features for you to explore. It has a ring modulator, flanger, stereo delay, routing options, 2. Related: I love free plugins, so I put together a list of the best Free Synth VST Plugins out there which you can check out here, Sonatina Symphonic Orchestra (Windows) The Sonatina Symphonic Orchestra Module contains the full SSO by Mattias Westlund, in one simple VST plugin (32 & 64bit).
You have to set up some VST host to play MIDI using this synth. It can be your favorite player, but you need to find a plugin, which allows to play MIDI files through VSTi. Some instructions are provided below. Use the bi2_polkovnik.mid (35KB) for checking your setup, it has to sound exactly as the bi2_polkovnik_syxg50.ogg (2.0MB).
VST MIDI Driver allows to use any VSTi as a global system MIDI synth. In this case every game or MIDI player, which uses the default system MIDI synth, will use Yamaha S-YXG50.
VST MIDI Driver supports Windows XP/Vista/7+, but on the Windows XP it is better to use the official Yamaha S-YXG50 WDM driver, which you can download from the Microsoft Windows Update servers: 4MB version (better quality, consumes more RAM), 2MB version (worse quality, consumes less RAM). This WDM driver can be installed manually using Add Hardware master in the Control Panel. Don't forget to set Yamaha S-YXG50 as the default system MIDI synth in the Sound settings. VSTi version of this synth is not needed when Yamaha S-YXG50 WDM is used.
foobar2000 doesn't use the system MIDI synth, but it is not a disadvantage. It allows to use Yamaha S-YXG50 VSTi witout installing any system drivers, which is much more safe.