Tom Clancy's Splinter Cell: Pandora Tomorrow's Soundtrack was a joint composition by musicians Jack Wall (Cutscenes) and Lalo Schifrin (Main Theme), as well as Guy Dubuc and Marc Lessard who composed the in-game music.
Splinter Cell: Essentials also features snippets of tracks found in this soundtrack. Guy Dubuc and Marc Lessard are the credited composers for Splinter Cell: Essentials.
The soundtrack was never officially released commercially, causing fans to rip and compile soundtracks from the game itself. Neither Ubisoft nor the composers have made any official statements towards the unknown composer, or non-profit releases of the soundtrack. It should be warned that commercial usage of such rips (paid distribution, ie: selling) is illegal under DMCA, which is upheld by most music distributors. Listening for the sole purpose of personal entertainment or unpaid distribution (download links, etc.) is typically safe, and in most cases perfectly legal.
The best available quality of the soundtrack in 36kHz is available at: