This tune is actually very old indeed and harks back to the halycon days of when I was still using some of the most clapped out synths you could ever find. The Casios always had a low grade buzz appeal to them. They were so feeble that they were almost comical, and yet they still held a weird charm of their own. The CZ series (much beloved of a variety of pop bands in the 1980s) actually managed to convey a fair imitation of a bass pedal given the right amount of reverb, and the FM piano sounds on the samplers (replete with whistle) still sounds suitably disembodied for these purposes.
Subsequent overdubs have been made to bring the piece up to date. Don't worry about your speakers. The sound really does drop out about halfway through, just as you reach the end of a dark corridor and hear the cathedral sounds drifting through the air towards you.
Something is watchng you. Something is probably standing right behind you.
This is also available on YouTube.
Instrumentation: