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


Not the most expensive, not the best reviewed, not the biggest, but the most FUN.  You know, that ONE that just makes you throw on some more music and keep listening, the one that makes your toes tap, your head bob, your ass move the most.  The one that makes you think to yourself "damn, why doesn't everyone have a pair of these?" Let 'er rip. 
shtinkydog
The most fun speakers I owned were a pair of G. R. Research OB7's. I did many experiments with them to test the orthodoxies extolled in audio magazines and books on how to create the ultimate stereo system. I tried bi-amplification with the tweeters on their own 245 SET amps and the midrange (2 5" cones open baffle) and the low frequency (4 5" cones sealed box). Then I read about the Wavac 833-A stereo and I made a pair of 833-A SET monoblocks which I connected to the low frequency speakers. Separating the tweeters from the midrange by powering them with separate 245 SET amplifiers sounded better than running both the tweeters and the midrange on the same amplifier. Active crossovers made of resistor and capacitor networks inserted between the mu-follower 6SN7 drivers sounded good and they are supposed to sound better than passive speaker crossovers. But the passive crossovers sounded better. Finally, I tried running the speakers on only 833-A's to all three speaker elements and this sounded better than anything I had tried before. I learned that not everything which is supposed to be the best way to run amplifiers and speakers applies universally to every system and I should not be surprised because speakers costing over $50,000 use passive crossovers.
Eventually I upgraded to Magnepan 0.7's the biggest Magnepans I can fit in my small house of 500 square feet floor space including the bedroom, the shower room, and an open kitchen because I was put off by the complications of cone speakers, their need to have elaborate notch filters in addition to high and low pass filters for crossovers, and boxes which require so much bracing, lined with sound deadener layers inside. I auditioned the Magnepans and they sounded more like live performances in the opera house where I go than any $50,000 speakers I had heard. But you can't drive them with thw 300B, let alone the 245 SET because they are insensitive. That is the price for circumventing the excessive variations and complications caused by back EMF of cone speakers influenced by the surrounds and even the cone material and the cabinets, all with resonances and wild variations in output with respect to frequency. When I got them home they sounded even better with the 833-A's driving them.
GR Research has impressive speaker kits which rival 4 figure factory made speakers and they are well suited for low power SET amplifiers if you don't want to use tubes which take 100 Watts just to heat the cathodes.
It seems whatever speakers I have are the most fun, modifying speakers is my idea of fun. Dahlquist DQ10, mirror image and internal wiring mods. Various models of Alon's, cabinet and driver mods. Merlin VSM-MM, just about every part within BAM and Duelund VSF caps in speaker. Present Klipschorns, every single thing modified with exception of bass portion of cabinet.
I generally keep speakers for many years, by doing mods over relatively long periods of time I create better synergy with partnering equipment. Tuning my system by ear, and for relatively little expense is both great fun and devoid of the audiophile nervosa equipment churning brings me.
And I still have both the Dahlquists and Merlins, can't bring myself to sell them. Dahlquists have been in storage for thirty years, perhaps someday I'll reinstate them. Hearing DQ10's,  Maggies and Dynaco speakers in various high end systems back in the 1970's brought me first awareness of high fidelity.
MartinLogan CLS's, which I still have.  Ok, so you have to learn how to NOT move your head from side to side, even a little, but once you get that down, what a blast.
When I was a young pup, my first "floor standing" speakers were a pair of used Wharfedale W70's with big, 12"+ woofers.  I remember that when the cannons went off at the end of the 1812 Overture, walls shaked and people ran for cover!
Speakers have provided much of my fun in 60 years of audio.  The RTR-6 ESL's were unique; several of us modified them with cork facing to emphasize their dipole character.  They produced the best high end I've ever heard.  They mated well with RTR 180's and 280's (both rather average), but when Bud Fried came out with the H kit, their overall character was more appealing.  Could never mate the 6's with that outstanding Fried transmission line woofer, or any other system, for that matter, but always missed that high end clarity.  Also built Fried's last C-3L's and his matching subwoofers (SM-3's), a system that can still "disappear."  Just now finishing Linkwitz's LX-521's, a project that takes some dedication.  Amen to those who mentioned Bob Fulton, a real gentleman and interestingly oblique thinker, as exemplified by his J's.  Still have a number of his fine recordings of amateur groups.