Which pair of speakers changed your Hifi life?

For me it was the discovery of planar speakers in the middle 70's.  First it was a pair of Magnaplanars..   Wow.  I was completely blown away.  once I got them set up for my room (placement and toe in).. the imaging and scale of the presentation both left to right and top to bottom,... wow.  

Maggies were the best I could afford for most of my adult life.  paired with reasonable priced electronics (lower end models of high end brands).  Then about 15 years ago I got into tubes, primarily triode designs.... and got my hands on modern Quads.  The Quad 2805 ESL speakers.  Another huuuuuge wow.  Of course it was not only the Quads.  I had gone from a total system cost of about 10-12k including everything to a system cost of about 80k,  Shindo Monbrison Pre (later upgraded to Shindo Masseto Pre), Air Tight ATM-3 mono blocs..   great turntable.  Wavelength Audio Tube DAC.. . Crimson model with the upgraded silver wiring and silver transformers.... top end end all DAC.  

But I gotta say, those Quad 2805s properly positioned in the room, driven by great electronics took my audio to an entirely new and better level.  

Had to sell most of it a few years ago due to a 'situation' our family had to deal with.  now working to rebuild a similar system over the next couple years.

So, my answer: QUAD ESL's considered by many to be 'the best' or 'one of the best speakers ever'.  .... 

I also listened to a great pair of original Quad 57's ESL's with a low power amp in a near field position.. sublime.

So again.. the QUAD ESL is the speaker that really did it for me.

Sound Lab Millennium 1, a large full-range electrostatic.  I bought the first pair in 1999, unseen and unheard, and they impressed me so much that I changed careers (taking a big pay cut) and became a high-end audio dealer.  

The first time I heard Classic Audio loudspeakers was also transformational, as they started me on the path to becoming a hybrid horn loudspeaker manufacturer. 

Duke

A long time ago. They were Dunlavy SC4 set up well in a store. I then experienced not "you are there", "they are here" as it sounded like the performer was in the room.

My first pair of Maggies in the late 70s opened my eyes (and ears) to the open, spacious sound of dipoles with excellent sound stage and detail.  I've owned several pair over the years, but often alternated with dynamic box speakers to get more "slam". 
 

More recently, I built a set of GR-Research NX-Oticas which really opened my eyes to what open baffle had to offer. Finally, I have a speaker system with the dynamics and slam I crave from the best box speakers I've owned, with the open, airy sound stage and great imaging of dipoles. 

Quad 57's! Bought the first pair in 1981. Stupidly sold them in 2000. Several years ago I bought two pairs of 57's. A classic design that still sounds better than most any box speaker!