SFZ is a high quality sample player.

Main Engine:

High Quality band limiting sample-playback engine.
9 quality settings to allow precise CPU usage optimisation.
256 voices of polyphony, unlimited layers per voice.
Per-channel polyphony limiter.
Fully Multi-timbral operation, supports all 16 MIDI channels.
Supports any standard/custom samplerate, including 22k, 32k, 44.1k, 48k, 88.2k, 96k, 192k and 384k.
Extensive SoundFont compatibility.
Several loading modes: Whole SoundFont, Single Program, Direct-from-Disk streaming.
Stereo Output.

Sound Generator:

A LPF, two LFOs and two Envelope Generators per layer.
Filter Cutoff, Filter Resonance, Keyboard Tracking, Velocity Tracking and Envelope Amount.
Vibrato LFO with Delay, Speed and Depth control.
Modulation LFO with Delay, Depth, Filter Depth, Pitch Depth and Amp Depth controls.
Modulation EG with Attack, Hold, Keyboard-To-Hold, Decay, Keyboard-To-Decay, Sustain, Release and Pitch Depth controls.
Amplifier EG with Delay, Attack, Hold, Keyboard-To-Hold, Decay, Keyboard-To-Decay, Sustain and Release controls.

Effects:

Programs / Banks:

128 internal programs (scenes).
Saves and Loads standard program (.fxp) files (saving only possible using the microHost, loading thru drag-and-drop operation).
Drag and drop support for program files (.fxp) and SoundFont files (.sf2).
All settings saved in the song.

Graphic User Interface:

MIDI implementation:

Extensive MIDI implementation: Velocity, Pitch Bend, Modulation, Sustain Sw and a lot more.

ASIO microHost:

Ultra light ASIO host for live performance and programming (90k).
Supports 44.1, 48, 88.2 and 96 kHz samplerates.
Virtual keyboard with PitchBend/Modulation/Program Change/Transpose controls using PC keyboard.
Simultaneous use of multiple MIDI ports.
Saves 16-bit and 32-bit WAV files direct-to-disk.

You can download SFZ Buddy to access hidden parameters in SFZ.