Ah! I wondered about the 14-bit audio trick, but I didn't realise it was that crisp. Also, I thought I heard stereo panning, which I didn't think was possible with the 14-bit audio track. Maybe it was mono, though.
With 14 bits you get 2 channels, so yes, it's in stereo

So, was the PCM track composed at all on an Amiga? I'm assuming with a PCM audio track, this demo does not fit on a single floppy!
To be honest, I don't know what the track was composed on, I got it from Jazzcat as an mp3-file and converted that to adpcm. And no, the demo most certainly doesn't fit on a single floppy as it requires several megabytes of diskspace.