J.S. Bach: Toccata & Fugue in D Minor, BWV 565 (Michael Murray)
Excellent recording by Michael Murray, played on one of the largest organs in the world. It sounds absolutely massive. The lows in this piece will make your house shake.
That one is a brilliant brilliant version, but my favorite is Xaver Varnus because of the sound of the organ itself, in the venue.
T&c is my favorite classical piece, has been since I was a kid. I'm not particularly into classical on any deep level or anything, but when a 9 year old is asking for a cassette of it, you know it's good lol