FluidSynth is a cross-platform real-time software synthesizer based on the SoundFont 2 specifications. Written by David Henningsson, Joshua Green and Pedro Lopez-Cabanillas
It features enhanced sound synthesis through standard interfaces like:

The ASIO interface can be used also on non native ASIO soundcards using ASIO4ALL. Just download and install the drivers from the ASIO4ALL website

SoundFont

SoundFont is a file format for sample based instrument sounds.
Starting from version 3.0, ScoreDate supports loading SoundFont 2.0 banks through the Fluidsynth engine
Following some useful links that can help ScoreDate users to find and choose the best sounds for their purpose.
Please note: some bank in "sfark" format will require SfArk to extract the SF2 bank