What is the most FUN pair of speakers you've ever had and why?

It was the fall of 1971 I was a junior in HS and I used every dollar I made bussing tables at a restaurant down the shore over the summer to buy a system package from a chain outfit called Tech Hifi in Bryn Mawr Pa.  The package consisted of a Dual 1219 turntable, a Harman Kardon 610 receiver and a pair of Large Advents.  The whole thing retailed for around $600.  I hooked it up in my bedroom and listened to Tumbleweed Connection.   Pure bliss.   It was the moment that I became an audiophile.  I never looked back.  While my current rig blows that little system away I still have a great deal of fondness for it.  I attribute that to the Advents.

B&W DM 602s

Driven by an Acurus A80, B&K Pro 5, and Cambridge Audio CD6. Interconnects were Nordost Black Knight, SC was Kimber. 

Right out of college, this system was dynamic, authoritative, and played at extremely loud volume with clarity and great fun.

Terrific speakers for a party. 

Another vote for the ESS AMT monitors... actually still have them (picked up used for $450 in the early 90's) and are in use daily.   

Infinity 1.5, with 12” dual Watkins woofers & emit tweeters.  Bought them used in 1980, and they still rock.  Ran them back then with a Hafler DH-500, paired with an Adcom GTP-500 II and a Technics SL-1200 (Stanton 681EEE).  I used to take them to parties and it would shake a room, I even set them up in gyms, and people would be amazed at the sound.  In today’s standards, they’re not that accurate, but when you turn them up with a stable amp, they can still amaze you.

I too had a pair of Altec 19s..ran with S.A.E 2400L 200 watt or so amp...man did I rock back then.