If you want the SoundFont to behave like an internal patch (without a computer), you must:

Before diving into SoundFonts, let's establish the hardware. The Edirol SD-90 (often bundled with the companion SD-80 as a smaller sibling) is a 1U rackmount sound module and USB audio/MIDI interface.

Key specifications:

The stock sounds are excellent (pianos, orchestral hits, synth pads), but by 2003, the sounds were starting to feel "dated." The secret weapon? The manual mentions a feature called "User Sample Import" — which is Roland/Edirol’s specific implementation of the SoundFont 2.0 standard.

To use SoundFont .sf2 libraries through the SD-90, you must use a host computer (Windows/macOS) to convert/play the SoundFont, then route the audio back to the SD-90.

You might ask: "Why not just use a free VST like sforzando or BassMidi?"

The answer is latency and feel. The SD-90 processes MIDI via hardware DSP (digital signal processor). The timing is rock-solid. When you play a MIDI keyboard into your DAW and monitor the SD-90, the response is snappier than any software sampler running through a bloated modern OS.

Furthermore, the SD-90 has a distinct "Roland top end" — a slight high-frequency roll-off that makes harsh digital samples sound warm and "taped." Loading low-bitrate SoundFonts from the 90s into the SD-90 produces a sound that is mathematically imperfect but musically rich in a way pure software cannot replicate.