The best speaker you ever heard?

In my opinion, the speaker is by far the most important part of the audio system. After all, it is the only part you hear. OK, the other stuff really matters a lot, but without a great speaker... No go.

I am a bit 'speaker-obsessed' I guess, and now I am wondering: What are the best speakers you have ever heard, and what made them the best?
Personally, I love Megaboom 3 and JBL Xtreme 2. They're both solid and stylish speakers. Of course, UE's speaker is definitely superior, but Xtreme 2 seems to be nice too. I'd recommend Review Position if you're planning to do research and head-to-head comparisons. They're really good and know what's what. 
Ok here we go again. The best speaker you ever heard is the first really good or distinct sounding speaker you heard in your youth. Your hearing was better and there will be nothing that sounds that good.
Not the best, but most memorable. In a dorm room, pair of KLH 17s driven by Dynaco st-70 playing Doors Hello I Love You.  Punchy juicy sound, probably colored with distortions.  But, boy, I loved it.