Thanks for everyone's comments.

Generally, I use my own files and synths, but occasionally I just want to hear a GM MIDI file to see if it is suitable for some other purpose.

The Coyote is fine for that and TTS-1 is also quite good (even the generic Microsoft synth is ok for simple audition).

Basically, I just want to avoid setting up all the MIDI channels and presets just to hear a MIDI file.