The pair I wish I'd never sold was a pair I'd built myself. It was a Klipschorn-copy design. A co-worker in Seattle had built the woofer section from plans, pretty solidly. I U-Haul'ed them back to Tucson at the end of the summer of '77, and got Electro-Voice tweeters and mid-range drivers for the wide, fiberglass "squawkers" as Paul Klipsch would call them, made a crossover (6/12), winding the huge coils myself. After tripping the protection circuit on my friend's 60 watt Kenmore, the gal from downstairs came to check on us because "It sounded like the stove fell over!" I even got them to look presentable in a rustic way, with thick, bold-grained, dark-stained paneling, and white burlap grill clothes for the top and sides.
A couple years later my friend bought them from me, and got two GAS Grandson amps (80 watts @ 4 Ohms), and I made passive cross-overs for bi-amping them, retaining the speaker crossovers too. The windows at his house sort of served as audible VU meters, buzzing along with the VU meters on the amps! In the living room it was downright adrenaline producing, crazy, thumping, loudest-rock-concert-you'd-ever-been-to loud, maybe 120 dB? And crystal clear, too (well, aside from the windows... ;)
As I said, crazy, but also impossible to get with, say, Quads.
Now that I am settled down, I wish I still had them. My friend still has the amps, but lent the speakers to another for safekeeping, but lost track of him over time...