The JV-1080 is a sample-based synth with a specific architecture (4 partials, TVF filters, dual LFOs). By converting or loading SF2 files (via SysEx or modern librarian tools like JV-1080 SoundFont Manager ), you are essentially tricking the Roland into thinking an external sample library is a built-in waveform. This turns a static 16MB ROM box into a semi-open sampler.