Which components knocked you out on first listen?

I haven't listened to the more esoteric stuff, just haven't lived in an area that sells it, but in my experience based on my local dealers (Washington DC area), these pieces absolutely floored me on first listen:
Ayre V-3 amp
Goldmund Mimesis 29 amp
ARC VT100 MkIII amp
Van den Hul MC-One cartridge on a full-blown Linn LP12 (circa 1991)
Linn Linto phono stage
Linn 5140 speakers (circa 1998)
ATC Active 50 speakers (circa 1993)
B&W Matrix 801 and 805 speakers (circa 1991)
Spendor BC3 speakers w/British Fidelity A3 amp (circa 1987)
Genesis 500 speakers
Vandersteen 5's
B&O Beogram 3000 turntable (circa 1975)
B&O linear tracking turntable (4004?) (circa 1978)
CAL Tempest II CD player (circa 1991)
Linn CD12 CD player
Transparent Ultra and Reference line of cables (circa 1994)Ensemble line of cables and power conditioning stuff
full on Meridian home theater/music system (circa 2000).

Also want to add to my list two components I am currently using together--agree w/TOK 20000 about the ARC CA-50:
ARC CA-50 integrated paired w/Proac Response 1SC's: I love this sound as much as that of my big "reference" system (Genesis 500's w/ARC VT100 MkIII and BAT VK30SE ). It absolutely floored me when I first hooked it up! And both pieces bought used here on Audiogon, in perfect shape.

This thread should yield some interesting things.
My examples are retrospective:

For speakers, The Revel Ultima Salon on piano playback.

For source material: The first time I heard Red Book CD on a player with upsampling.

For amplifiers: The first time I heard Krell bass make my stomach muscles tighten.

Preamplifiers: CJ tubes on Jazz

Not examples to build a system around, but certainly moments that lifted mine eyes up into the hills ...

Legacy Audio Focus 20/20 loudspeakers

I live for soundstage and there has been nothing better than my first listen to the Audible Illusion 3A tube pre-amp and the JM Labs Daline 6.1 speakers. W-i-d-e, D-e-e-p and T-a-l-l.